radiotherapy in gynaecology

Radiotherapy In Gynaecology

Prof. M.C.BansalMBBS., MS., FICOG., MICOG.

Founder Principal & Controller,Jhalawar Medical College & Hospital

Jjalawar.MGMC & Hospital , sitapura ., Jaipur

RADIOTHERAPY IN GYNAECOLOGY

Introduction Radiotherapy plays a major role in the treatment

of patients with Gynaecological malignancies. Computer technology and information system have transformed many aspects of radiotherapy practices in last two decades.

Three dimensional treatment planning based on computed tomography (CT)and MRI, optimized inverse planning , computer controlled treatment delivery and remote after loading Brachytherapy.


Introduction(contd) these techniques enable radiation oncologists to restrict radiation dose distribution to specified target volumes . Maximal dose is delivered to tumor ,while normal

tissue is spared as much as possible. In1999 –2000 , results of randomized clinical trials

demonstrated a significant improvement in pelvic disease control and survival when concurrent chemotherapy was added to radiotherapy for patients with locally advanced cervical cancer.

.


Radiation Biology Cellular effects of ionizing 1. Cellular death defined as the loss of clonogenic capacity e.g.

inability to reproduce because of mitotic cell death. 2. Ionizing radiation may also cause programmed cell death

(apoptosis) 3. The critical target for most radiation induced cell death is the

DNA within the cells nucleus - Photons or charged particles inter act with intra cellular water to produce free radicals . Free radicals interact with DNA causing Breakage –Inability to reproduce.

4. Such Reproductive cell death may not be expressed morphologically until days and months . Some cells may still continue to divide before they die.

5. Apoptosis ( programmed cell death) may also play an important role in radiation induced cell death. The plasma membrane and nuclear DNA may both be important targets for this type of death.


FractinationConventional radiotherapy is usually given in

a fractionated course with daily doses of 180-200 cGy ( centi Gray)

The difference between the Fractionation sensitivity of tumors and normal cells is an important determinant of the theraputic ratio of fractionated irradiation.

RADIOTHERAPY IN GYNAECOLOGY Dose Rate Effect

As dose rate is decreased , tissue have more chance to tolerate the insult and repair from sublethal injury during therapy. This is called the Dose rate effect.

RADIOTHERAPY IN GYNAECOLOGY The four R’S

The biological effect of a given dose of radiation is influenced by the Dose, Fraction size, Inter fraction interval and time over which the dose is given.

Four R’s of radio-biology 1. Repair. 2.Repopulation 3.Redistribution. 4.Reoxygenation.

These Four govern the influence of dose ,time and fractionation on the cellular response to radiation.

.

RADIOTHERAPY IN GYNAECOLOGY Repair

Fraction irradiation permits greater recovery of sublethal injury during treatment , a higher dose of radiation is needed , to achieve a required biological effect when total dose is divided in to smaller fractions.

Altered fractionation protocols usually require a minimum interval of 4- 6 hours between treatment

RADIOTHERAPY IN GYNAECOLOGY Repopulation

Repopulation refers to the cell proliferation during the delivery of radiation.

The magnitude of the effect of repopulation on the dose required to produce cell death depends upon the doubling time of the cells involved. For cells with a relatively short doubling time ,a significant increase may be required to compensate for a protraction in the delivery time.

RADIOTHERAPY IN GYNAECOLOGY Repopulation

The speed of repopulation of normal tissue that manifest radiation injury soon after exposure (skin, mucosal surfaces etc).

Treatments including chemotherapy, radiotherapy, surgery = its tissue response is lethal as well as an increase in proliferation of surviving cells(clonogens).

This accelerated repopulation may increase the detrimental effect of treatment delays.

It may influence the effectiveness of sequential multimodality treatments

RADIOTHERAPY IN GYNAECOL0GY Redistribution

Study of synchronized cell population have shown differences in the radio sensitivity of cells in different phases of cell cycle.

Cells are most sensitive in the late G1 phase and during mitosis . More resistant in mid to late S and early G1 phases.

When synchronous dividing cells receive a fractionated dose of radiation , the first fraction tends to synchronize the cells by killing off those cells who are in most sensitive phase.

Cells those in phase S begin to progress to more sensitive phase. during the interval between two fraction delivery.

This phenomenon gives overall increased cellular death if cells have short cell cycle.

RADIOTHERAPY IN GYNAECOLOGY Re oxygenation

The sensitivity of fully oxygenated cells to sparsely ionizing radiation is approximately 3 times more than anoxic cells.

O2 is most effective radiation sensitizer.

It is believed that O2 stabilizes the reactive free radicals produced by ionization.

RADIOTHERAPY IN GYNAECOLOGY Over coming Radio resistance

Many treatment strategies have been explored to overcome the relative radio resistance of hypoxic cells in human solid tumor.

1. Hyperbaric oxygen or carbogen breathing 2. Red cell transfusion or growth factor. 3. Pharmacological agents e.g. Metronidazole , it

acts as hypoxic cell sensitizer. 4. High linear –energy transfer radiation. tumor hypoxia continues to be one probable cause of the failure of irradiation.

RADIOTHERAPY IN GYNAECOLOGY Linear Energy Transfer &

Relative Biological EffectivenessThe rate of deposition of energy along the

path of radiation beam is called Linear energy Transfer .

Photons, high energy electrons, protons produce sparsely ionizing radiation beam of low energy transfer.

Larger atomic particles e.g. neutrons and alpha produce much more densely ionizing beam with high linear energy transfer.

RADIOTHERAPY IN GYNAECOLOGY High linear transfer beam

The high linear energy transfer beam: 1.There is a little or no repairable injury to

tumor cells. 2.The magnitude of cell death from a given

dose is greater. 3.The oxygen enhancement ratio is diminished. the high linear transfer beam’s use in the treatment of gynaeclogical malignancies had

no major impact in producing results.

RADIOTHERAPY IN GYNAECOLOGY Hyperthermia

Temperature is another factor which may modify the effect of radiation.

Temperature in the range of 42-43 degree centigrade sensitize cells to radiation.

This approach has given encouraging

results but technical problems still limit its wide use.

RADIOTHERAPY IN GYNAECOLOGY Interaction between Radiation & Drugs

Drugs and radiation interact in many different ways and modify cellular response.

Steel & Packham categorize these interaction in Four groups

1.Spatial cooperation- Drugs and radiation act independently at different target and with different mechanism so that total effect is equal to the sum of effects of individuals .

2.Addivity—when two agents act on same target to cause damage – equal to sum of their individual toxic effect.

RADIOTHERAPY IN GYNAECOLOGY Interaction Between Radiation & Drugs

3. Supra additivity—The drug potentiates the effect of radiation , causing a greater

response than expected from simple additivity.

4. Sub additivity—The amount of cell death is less from use of two agents simultaneously.

RADIOTHERAPY IN GYNAECOLOGY Therapeutic Ratio

The difference between tumor control and normal tissue complications is referred to as Therapeutic Gain? Therapeutic Ratio.

Primary aim of research in radiotherapy is to improve therapeutic ratio by increasing separation between these dose response curves, maximizing the probability of complication free tumor control.

RADIOTHERAPY IN GYNAECOLOGY Effects of Radiation on Normal Tissue

Effect of radiation on normal tissue depends upon many factors :-

1. Radiation dose, the target organ, volume of tissue irradiated and division rate of irradiated cells.

2. Tissue that have rapid cell turnover (e.g. tissue which require constant cell removal like skin , mucosal epithelium , hair , bone marrow , reproductive tissue etc) tend to manifest radiation injury soon after irradiation.

3. Tissues whose functional activity does not require constant cell removal tend to manifest radiation injury late after months/years. Examples of late reacting tissues are connective , muscle and neural tissue. Some normal tissue may die through mechanism of apoptosis e.g. lymphocytes , salivary gland cells and intestinal crypt cells.

RADIOTHERAPY IN GYNAECOLOGY Effect of Radiation on Normal Tissue

Acute Reaction Acute reaction to pelvic radiation , such as diarrhea is associated with mucosal denudation .The severity of acute reaction depends upon nature and volume of normal tissue , dose of radiation , interval between two fractions .

Late Reaction It results from 1. Damage to vascular Struma that causes an

epithelial proliferation with decreased blood supply and subsequent fibrosis.

2.Damage to slowly or in frequently proliferating paranchymal stem cells it eventually results in loss of functional capacity.

RADIOTHERAPY IN GYNAECOLOGY Effect of Radiation on Normal Tissue

For a given dose of radiation administered over a given time interval , Risk of late effects is more with larger fraction.

1. Uterus and cervix are typically described as radio resistant except their mucosal linings.

2. Ovary is highly sensitive , it may lead to iatrogenic ovarian failure which is dose dependent as well as modulated by age of patient.

Pre-menarcheal girls exposed to 30 Gy dose may continue to have mansturation and even may carry pregnancy to term . Although they experience premature ovarian failure later.

Most adult women develop premature failure after 20 Gy.

RADIOTHERAPY IN GYNAECOLOGY Effect Of Radiation On

Normal Tissue

3. Vagina-- the Radiation tolerance varies with site , duration as well as radiation dose. Apical vagina require higher dose for atrophic changes , shortening and loss of its elasticity as compared to other areas.

4.Vulva can withstand some Radiation similar to skin.

RADIOTHERAPY IN GYNAECOLOGY Effect Of Radiation

ORGAN Tolerance Dose Risk dose / serious side effects

1.Small intestine

2.Rectum

3.Ureter

4.Kidneys

4.Liver

5.Spinal cord & Nerves

6.Bone

30Gy

45-50 Gy

85-90 Gy

18-22 Gy to both

30 Gy

<50 Gy 50 - 60 Gy

<10 Gy 30-40 Gy

Diarrhea , Chronic Obstruction

Bleeding , fistula , obstruction .Risk of stricture .

Renal hypertension & failure

Hepatic dysfunction

Uncommon Caudal equina

Bone marrow resting tissue fails to repopulate Aplastic anaemia , pathological Fractures.

RADIOTHERAPY IN GYNAECOLOGY Treatment Strategies

1.Hyper fractionation Dose per fraction is reduced , number of fractions and total dose is increased , but total time of treatment remains unchanged.

Treatment is usually given 2-3 times per day at the interval of 6-8 hrs

2.Accelerated Fractionation Dose per fraction is unchanged , over all duration of radiation is reduced , total dose is reduced or remain unchanged . It does not reduce the incidence of late effects but increases the acute effect of treatment.

3.Hypofractionation usually avoided . Necessary reduction in dose reduces the likelihood of complete eradication of tumor with in the treatment field. Rx of malignant Melanoma is treated by this strategy , HDR brachytherapy used to achieve it.

RADIOTHERAPY IN GYNAECOLOGY Combination Of Surgery and

Radiotherapy

Because both are effective treatment . Surgery removes bulky tumor that may be difficult to control with tolerable dose of radiation. Combined radiation will sterilize the tumor bed and regional /distant Lymph Nodes.

1. Pre operative irradiation 2. Surgical staging followed by definite irradiation. 3. Intra operative irradiation. 4. Surgical resection following Post operative

irradiation 5. Combination of these approaches.

RADIOTHERAPY IN GYNAECOLOGY 1. Preoperative Irradiation

It is used to make the inoperable tumor –operable , example Ovarian Tumor , II stage Endometrial Cancer , bulky Ca Cervix .

The greatest risk of this approach is that if tumor remains un resectable , the effect of further irradiation will be markedly decreased by increased interval between two treatment plans.

RADIOTHERAPY IN GYNAECOLOGY 2. Intraoperative

In some cases intra operative irradiation can be delivered with a permanent implant (using 125 I or 198 Au )with after loading catheters in the operative bed or by ortho voltage unit in OT.

RADIOTHERAPY IN GYNAECOLOGY 3. Post Operative Irradiation

It has been demonstrated to improve local, regional control.

In Vulva cancer ,post operative pelvic and groin irradiation reduces the risk of recurrence and improves patient’s survival.

Same is true for Ca Cervix and Endometrium With +ve lymph nodes.

RADIOTHERAPY IN GYNAECOLOGY Combination Approaches

Combined therapy is optimized when treatment plan exploits the complimentary advantages of both treatment.

It carries higher degree of morbidity.It should be limited to situation in which

combined approach is likely to improve survival ,permit organ preservation, significantly less risk of local recurrence compared to the expected result from either modality alone.

RADIOTHERAPY IN GYNAECOLOGY Physical Principles

Ionizing radiation lies in the high energy portion of the electromagnetic spectrum .

Characterized by their ability to excite or ionize the atoms in absorbing material.

The Nuclear decay of radioactive nuclei can produce several types of radiations , including uncharged Gamma(Y) rays , negatively charged beta rays (B) electrons , Positively charged alpha (a) particles (Helium ions) and neutrons .

The resulting ionizing radiations are exploited therapeutically in Brachytherapy( using 226 Ra ,137 Cs 186 Ir and other isotopes ) .

To produce Teletherapy Beams (e.g. 60 Co )The average energy of the photons produced by the

decaying radioactive Cobalt is 1.2 million electron Volts (Me V) .

RADIOTHERAPY IN GYNAECOLOGY Interaction of Radiation & Matter

X Rays and Y rays Photons interact with matter by means of three distinct mechanisms : Photoelectric effect , compton scatter,and pair production.

Photo electric effect is used for diagnostic purpose--X rays having different absorbability by different tissue. Effect is proportional to Z3 . Z is the atomic number of the absorbing material.

Modern therapeutic beams of 1-20 mega volts produce photons that interact with tissue primarily by compton scatter.indepedant of Z . These photons produce an increasing number of electrons and ionization as they penetrate beneath the surface of absorbing material. Skin sparing effects and penetration of energy beams of 15 MeV or greater make them useful in pelvic treatment.

Pair production is related to Z2. this type of absorption begins to dominate only at photon energies of more than 30 MeV . It is of limited value in current radiation therapy planning.

RADIOTHERAPY IN GYNAECOLOGY Electron and other Particles

Several types of particle beams are used in radiation therapy: electron beam, proton beam and neutron beams.

Electrons are very light particles . When they interact with matter ,they loose their energy in a single interaction. Hence used to treat superficial targets without delivering significant dose to underlying tissue.

Protons are +vely charged particles ,much heavier than electrons.

Neutrons are neutral particles that tend to deposit most of their energy in a single intranuclear event. They are not used in gynaecology.

RADIOTHERAPY IN GYNAECOLOGY Measure of Absorbed Dose

Absorbed dose is a measure of energy deposited by the radiation source in the target material.

Unit currently used to measure radiation dose is the Gray(Gy) ,equal to 1 Joule per Kg of absorbing material.

1Rad= 1cGy= 100 rads.Safe radiation depends upon precise calibration

of radiation source activities and machine output.

Periodic calibration of equipment and sources are vital part of quality assurance in any radiotherapy department.

Relationship between radiation dose and surviving fraction of cells treated in vitro with radiation delivered in a single dose or in fractions. Top = Most tumors and acutely responding normal tissues. Bottom = Late-responding normal tissues. For most tumors and acutely responding normal tissues, the cellular response to single doses of radiation is described by a curve with a relatively shallow initial shoulder (Top, yellow line). Cellular survival curves for late-responding normal tissues (Bottom, yellow line) have a more pronounced shoulder, suggesting that these cells have a greater capacity to accumulate and repair sublethal radiation injury. When the total dose of radiation is delivered in several smaller fractions (Dose A [dose/fraction] = blue line, or a larger fraction Dose B [dose/fraction] = red line), the response to each fraction is similar and the overall radiation survival curve reflects multiple repetitions of the initial portion of the single-dose survival curve. Note that the total dose required to kill a specific proportion of the cells decreases as the dose per fraction increases (red line). Arrows indicate the differential effects of relatively large versus small fractions of radiation. The greater differential effects of fractionated irradiation on normal tissues (Bottom) than on tumor (Top) reflect the greater capacity of late-responding normal tissues to accumulate and repair sublethal radiation injury.

RADIOTHERAPY IN GYNAECOLOGY Inverse Square Law

The dose of radiation from a source to any point in space varies according to the inverse of square of the distance from the source to the point.

This relationship is particularly important for brachy therapy applications because it result in rapid fall off of dose as distance from intracavitary or interstitial source is increased.


Radiation therapy is delivered in three ways :-1.TeletherapyXrays are delivered from a source

at distance from the body(external beam therapy)

2.BrachytherapyRadiation source are put within OR adjacent to the target to be irradiated.(intra cavitary/interstitial) 3.Radioactive Solution solution that contain isotopes ( radioactive colloidal gold or 32 P) are instilled in in peritoneal cavity to treat the intra peritoneal metastatic nodules

RADIOTHERAPY IN GYNAECOLOGY Teletherapy

Several terms are used –Percentage depth dose – change in dose with depth along

the central axis of radiation beam.D max—The maximum dose delivered to the treated

tissue.Source to skin distance – distance between source of X

rays to skin surface.Iso center— a point in patient which remain constant at a

fixed distance from source even when source is rotated.Source to axis distance—distance between source to iso

center.Iso dose curve—is a line or surface that connects the

point of equal radiation dose.

Fig 4.7

Fig 4.8


Following factors influence the dose distribution in tissue from a single beam of photons--

1.Energy of beam –Higher energy photon beams are more penetrating than the low energy beam. Higher energy beam have a larger buildup region resulting in relative sparing of skin surface.

2.Distance from source to tissue—as the distance of source to skin surface increases ,the percentage depth dose increases.

3.The size of radiation field–the percentage depth increases with the increasing radiation field size.


4.The patient’s contour and the angle of the beams incidence.

5.The density of tissue in the largest volume.6.A variety of beam-shaping devices placed between

source and patient alter shape or distribution of radiation dose.

Most radiation therapy treatment combine two or more beams to create dose distribution designed to accomplish three aims

(i)Maximize dose delivered to tissue (ii)To produce homogenous dose within the

volume of tissue (iii)to minimize dose to healthy tissue.


Multiple fields may be used to focus the high dose region more closer to deep target volume.

Multi leaf collimators are computer controlled that can form irregularly shaped fields , replacing hand loading devices.

Recently attention has been focused on IMRT to optimize delivery of radiation from multiple beam angles.

The leaves of multi leaf collimators enter the field or retract dynamically to deliver desired dose of radiation to the tissue within target.

RADIOTHERAPY IN GYNAECOLOGY Brachy Therapy

It involves placement of radioactive source within the existing body cavity.Termed as intra cavitary treatment .

Most gynaecologic applications of intra cavitary therapy involves intrauterine/intra vaginal applicators that are subsequently loaded with encapsulated radioactive sources.

These applicators are consisting of hollow tube /tandem and intra vaginal ovoids /receptacles.

This technique has proven very useful in treatment of cervical cancer as it allows a very high dose of radiation to cervical , parametrial tissue & pelvic lymph nodes with out excessive radiation to surrounding normal tissue.

To minimize the exposure to medical personnel ,modern applicators are first placed ,their position is checked with x rays and then applicator system is loaded. Remote after loading devices are used to automatically retract sources from the applicator to a lead lined safe when some one enters the room.

Figure 4.11

Figure4.10

RADIOTHERAPY IN GYNAECOLOGY Isotopes Used in Gynaecological

Treatment

Element Isotope Half life Ey (MeV) Eb (MeV)

PhosphorusIodine

Cesium

Iridium

Gold

Radium

Cobalt E y,

gamma ray energy

32P125I

131I

137 Cs

192 Ir

198Au

229Ra

60 Co

E b beta ray energy

14.3 days60.2 days

8.06 days

30 yrs

74 days

2.7 Days

1,620 yrs

5.26 yrs

MeV Million Electron Volts

None0.028 avg

0.08-0.63

0.662

0.32-0.61

0.41-1.1

0.19-0.6

1.17-1.33

1.7( max)None

0.61(max)

0.514,1.17

0.24,0.67

0.96(max)

3.6(max)

0.313(max)

RADIOTHERAPY IN GYNAECOLOGY Dose Rate

Historically, most brachy therapy was delivered at low dose. Most commonly 40-60 cGy / hr

The advent of computer controlled remote after loading has made it possible to deliver higher doses.

HDR treatment is given as OPD procedure.In this technique a single very high activity source

of 192 Ir is loaded in the intra cavitary applicators.An alternative to HDR therapy commonly used in

Europe, has recently been replaced by Pulse Dose Rate (PDR) brachy therapy in USA.

The total brachy therapy dose to point A must be reduced when converting from LDR to HDR.

RADIOTHERAPY IN GYNAECOLOGY Dose rate

If the tumor is very large or vaginal anatomy is unfavorable, radiation doses to tumor and normal tissue may be same.

Dose fraction schemes used for HDR therapy produce tumor control and complication rates equivalent to LDR.

Increasing the number of fractions and concomitantly decreasing the dose per fraction reduces rate of moderate and severe complications.

Commonly used regimen in USA is % fraction of 5.5 -6 Gy each to point A , after 45 Gy to the pelvis with wide variation in fractions(2-13)and dose per fraction (3-9Gy).

RADIOTHERAPY IN GYNAECOLOGY Dose rate

the appropriate dose and dose per fraction is based on calculation on estimated biologically effective dose (BED) on tumor and normal tissue.

Bed= (nd)x (1+d/(a/b) where ,d is the dose per fraction

For example : Tumor BED = (30) x(1+6/10) = 48 GyNormal Tissue BED = (30)x( 1+6/3) = 90 Gy

RADIOTHERAPY IN GYNAECOLOGY Interstitial Therapy

It refers to the placement of radioactive source with in the tissue.

VARIOUS SOURCES OF RADIATION : Such as - 192Ir , 198Au , 125I , 103Pd , can be obtained as radioactive wires and seeds.

Sources can be positioned in the tumor/tumor bed in variety of ways

1.Permanent seed implants (usually125I,103Pd,198Au) can be inserted using a specialized seed inserter.

2. Temporary Teflon catheter implants can be placed intra operatively and subsequently loaded with radioactive source.

Complications of radiotherapyEarly Transient nausea and vomiting----

antiemetic drugs will help.Bladder and rectal irritationGIT irritation--. Anorexia , diarrhoea and

weight loss. octreotide is used.Malaise, irrtability,depression and headacheFlare up of sepsis

pyometra,t.o.masses,peritonitis ansepticaemia.

Cystiis, pyeliis, pyelonephritis.PyerexiaPulmonary Embolism.Skin reaction

Complications of radiotherapyLate complications

Persistant anaemia.Chronic pelvic pain followingfibrosis involving

nerve trunks.Pyometra.Proctiis--.rectal ulcer,bleeding,strcture and

rectovaginal fistula.Post radiation cystitis,ulcer,haemturea, UTI and

vesicovaginal fistula.Smallbowel strictures ,ulcers, obstruction, gut

perforation.Colonin-stricture,ulcer, telangiectasia,perforaton,

obstructiontropic vagints, ca, stenosis, dyspreunia.Ureterc obstruction and obstructive uropathy.Osteporosis and fracture neck of femur.Overian dysfunction/failureUterine sarcoma 8%

cases

Contra Indication To radiotherapySever anaemia.Poor general health.Sepsis.Pregnancy.Presence of fibroid in uerus.Tubo- ovarian masses.Utero vaginal prolapse.Fistulas.Radio resistant tumors

RADIOTHERAPY IN GYNAECOLOGY Interstitial Therapy

3.Temporary transperineal template guided interstitial needle implants can be placed using a Lucite template with regularly placed holes and a central obturator that can hold tanden or additional needles. Needles are after loaded with192 Ir. These implants are used to treat vaginal and some cervical tumors

4.Temporary transperineal implants can also be placed freehand an approach that may allow better control of needle placement in selected cases. Useful in treating vaginal and urethral cancers.

Most gynaecological implants are temporary LDR implants like intracavitary therapy. Interstitial therapy delivers a relatively high dose of radiation to a small volume sparing the surrounding normal tissues. The risk to normal tissue adjacent to tumor or in the tumor bed still will be significant, particularly when needle placement is inaccurate.

RADIOTHERAPY IN GYNAECOLOGY Intraperitoneal Radioisotopes

Radioactive phosphate(32P) and colloidal gold(198Au) used for treatment of epithelial cancers of ovary in an effort to address the transperitoneal spread of cancer .

If a radioisotope is evenly distributed within peritoneum , it is theoretically possible to irradiate the entire surface. However the energy deposition within the abdomen and the dose delivered beneath the peritoneal surface depends on many factors i.e. distribution of isotope and energy of decay product.

In practice isotope is seldom distributed evenly in peritoneal cavity and omental surface. This approach is rarely used now a days.

Half Life of commonly used Radio isotopes

Brachy therapy

Xray of pelvis showing position of radium in Manchestr insertion

RADIOTHERAPY IN GYNAECOLOGY Clinical uses of radiation

Cancer Cervix

The curative treatment of cancer cervix usually includes external pelvic irradiation and brachy therapy often with concurrent chemotherapy.

The goal of therapy is to eliminate cancer in cervix para cervical tissues and regional lymph nodes.

Because bulkiest tumor is usually in cervix, this region typically requires higher dose than the rest of pelvis to achieve loco regional control. Fortunately it is possible to deliver higher dose with intra cavitary therapy.


Cancer Cervix

Treatment Volume : Typical external- beam fields are designed to include

the primary tumor , para cervical iliac and pre sacral nodes ,all with 1.5- 2.5 cm margins. If common iliac and aortic nodes are involved, then the treatment fields are extended at least to lower para aortic region.

The borders of field are as follows 1.Inferior - at the mid pelvis / 2-3 cm below cervical lesion. 2.Superior - at the L4-5 interface / bifurcation of

aorta. 3.Lateral to pelvic lymph nodes 1-2cm / at east 1cm lateral to margin of bony pelvis.

Isodose curves of a standard radium insertion using the Manchester Technique in Ca Cx

Different methods of brachy therapy A. Manchester , B Paris , C. Stockholm.

Different methods of brachy therapy A. Manchester , B Paris ,

C. Stockholm.


Cancer Cervix

Using four beams (anterior, posterior, right and left lateral)rather than opposed pair of anterior and posterior beams may some times reduce volume of tissues irradiated to a high dose.

4 to 5 weeks (40 - 45 Gy ) of radiation and combined chemotherapy usually reduces endo cervical disease and shrinks exophytic tumor , fascilitating optimal intra cavitary therapy.

Intra cavitary therapy is critically important for successful treatment , even for patients with very bulky stage III tumors.


Cancer Cervix

Patient with FIGO stage IA can often be treated with intracavitary irradiation alone.

Most patients with stage IB1 have high risk of metastasis to pelvic lymph nodes , hence need atleast moderate dose of pelvic radiation (39.6Gy) to sterilize possible microscopic regional disease.

For patient of Ca Cx having vaginal bleeding haemostasis can be achieved with vaginal packing ,application of Monsel’s solution and rapid initiation of External Beam Irradiation.


Cancer Cervix

Radiation Dose-- 1.Point A – a point 2cm lateral and 2cm superior to external cervical os. 2.Point B - a point 3cm lateral to point A. The total dose to point A - from external beam and LDR

intacavitary therapy adequate to achieve central disease control is between 75 Gy (for IB1 stage) & 90 Gy (for bulky or locally advanced disease).

Prescribed dose to point B is 45-65Gy , depending on extent of parametrial and side wall disease.


Cancer Cervix

Prescription and treatment planning can not be limited to specification of the dose to these reference points . Other factors to be considered are as follows :— 1.The position and length of intrauterine tandem 2.The type and size of vaginal applicators. 3.Quality of vaginal packing. 4.The size of central tumor(before and after external beam therapy 5.The vaginal surface dose ( usually limited to 120 to 140 Gy). 6.Oroximity of system to bladder and rectum 7. The dose rate or fraction size. There is growing move toward use of image guided brachytherapy. Treatment planning based on CT / MRI images obtained with implant in place.


Cancer Cervix

Results of treatment : Radiation therapy is extremely effective in the treatment of stage IB1 . Disease control achieved in central and pelvic lesion is greater than 98%and 95% respectively. Pelvic control rate decreases as tumor size and FIGO stage increases. 5 year pelvic control rate of 50-60% even for bulky stage IIIB have been reported. During the past decade significant improvement in pelvic disease and survival when Cis-platin containing chemotherapy is delivered concurrently with radiation to patients with advanced pelvic lesions. 5 fluouracil a potent radiosensitizer is not that effective in Rx of Ca Cx . Mitomycin C and Epirubicin given along with radiotherapy also help control advanced disease.


Cancer Cervix

Adjuvant pelvic radiation after radical Hysterectomy.

For patient with stage IB and IIA Ca Cx who had radical hysterectomy along with pelvic lymphadenectomy , involvement of nodes is strongest predictor of local recurrence and death. Survival rate of patients with +ve nodes is 50-60% much lower than that achieved by chemo- radiotherapy. Post operative radiotherapy is must for them.

Patients with – ve nodes but bulky cervix > 4cm and deep stromal invasion also require post operative radiotherapy. Adjuvant radiotherapy carries high risk of complications and Patients who have high risk factors at initial evaluation should be treated by radical radio –chemotherapy.


Cancer Cervix

Recurrent Cervical cancerPatient who have an isolated pelvic

recurrence after radical hysterectomy can be treated by aggressive radiotherapy.

Patients with local recurrence with no fixation to bone/+ve pelvic nodes have 5 year survival rate as 60-70-%

Patient having +ve nodes/fixation to bone have very poor survival rate of 20% after radiotherapy.

Endo cervical Cancer

1.Chemotherapy. 2. Radiotherapy. 3. surgery all three are combined In endo cervcal cancer the best survival is seen when concomitant Cisplatin weekly and 6 weekly radiotherapy is followed by surgery.

Endometrial cancerAs adjuvant to surgery comprising : TAH-1-BSOBy administrating vaginal radiation via

colpostsat ,vaginal vault recurrence drops by 20%.

To prevent local vaginal recurrence which is reported in 13 %

The survival improves in stage 1C and II when post operative radiation is given to pelvic nodes.

It is indicated in Sarcoma.To treat pt unfit for surgery.To treat pt with pelvic/ vaginal recurrence.For palliation in cases of non resectable intra

pelvic / metastatic disease.s

Ovarian CancerPost surgery and chemotherapy ; “ Moving

Strip Technique “ of external radiation is applied to par aortic nodes and residual abdominal metastasis.

In this a strip of 2.5b cm area is radiated front and back(starting from pelvis) over 2days and then moved upwards until whole abdomen and back is irradiated.Liver and Kidneys are shielded.

The total tumor dose of 2600- 2800 cG y is administered.

CT and MRI are use ful in detecting involved para aortic and pelvic metastasis.

Ovarian Cancer----------Intra abdominal instillation of AU

198, P 34 and thiotepa is not used now a days owing to intestinal injury and adhesion formation.

Approximately 49-50% 5 year survival rate can be achieved in stage II.

5 year survival rate drops to 5-15% if larger residual lesions are left after intial surgery combined with chemotherapy.

Vulvar CancerThe aim of integrated multimodality therapy including surgery, chemo radio therapy is to reduce the risk of local, regional failure in patients with advanced primary or distant nodal involvement.

To obviate the need of exenteration in women having urethra , Anal extension of cancer.

The dose of radiation given is 4500-5000cGy to woman with microscopic disease and 6000-6400cGy to woman with macroscopic disease.

Pre operative Radium needles (60 Gy in 6 days) shrinks the tumor and facilitates extirepation of tumor at later date . Post operative radiotherapy is prefered to women with +ve inguinal nodes.

Vaginal Cancer

Radiotherapy is preferred then surgery.

If cancer is located in upper 1/3rd ., it is radiated as ca Cx.

If located in middle/ lower 1/3rd of vagina , interstitial needles (Iridium -192) are inserted in vaginal tumor.

Chorio Carcinoma

It respond well to chemotherapy which replaced surgery in young women.

Radio therapy is applicable in the distal metastasis in few cases.

radiotherapy in gynaecology

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