CERVICAL CANCERRT Technique

Mr.Kiattisak Promsensa

Introduction• Cervical cancer constitutes 6% of all

female cancers in the USA. • responsible for 1.6% of all cancer-related

mortality• 15% of all gynecologic cancer mortalities

in women • most common gynecological cancer in

developing and underdeveloped countries.

CA Cervix in Thailand• leading cancers in Thailand for female

population• seven women die from cervical cancer

each day• most common stage is stage I• most common histologic type was

squamous cell carcinoma, followed by adenocarcinoma

Sarikapan Wilailak, J Gynecol Oncol. 2009 June; 20(2): 81–83

Anatomy of the female genital tract

1. paracervical2. parametrial3. internal iliac4. external iliac5. common iliac6. presacral

Pathology

• Squamous cell carcinomamost common, ≈ 80%

• Adenocarcinoma, ≈ 15%

• Others

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Clinical characteristic of the cancer• exophytic or fungating• infiltrative• ulcerative

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Risk factors• early first intercourse• multiple partners• history of other STD’s• A male partner with multiple previous

sexual partners• high parity• smoking• immunosuppression• The presence of a cancer-associated

HPV(type 16, 18)

Clinical PresentationEarly• Postcoital bleeding• Irregular menstruation• Bloody discharge• Discharge with foul odor• Leg and groin painLate• Fistulas (cervicovesical, vesicovaginal,

cervicorectal, rectovaginal)• Hydronephrosis and renal dysfunction due to

ureter obstruction• Edema in lower extremities• Anemia

Screening for cervical cancer

• Screening with Pap smear decreases mortality by 70%

• ACS recommends screening for all women who are sexually active or >20 years old

• three normal annual exams after age 30• at least once every 3 years

Robbins and Cotran Pathologic Basis of Disease 7ed

Initial evaluation• complete history and physical examination• colposcopy ± conization/biopsy• full pelvic exam• cysto+proctoscopy• Laboratories: CBC, LFTs, chemistries, BUN/Cr,

urinalysis• CXR, IVP• If stage IIIB, place renal stent prior to starting

chemo

Staging (FIGO 2008)

• Stage I. Carcinoma strictly confined to the cervix; extension to the uterine corpus should be disregarded– IA : Microscopically• IA1 : depth ≤ 3 mm., diameter ≤ 7 mm.• IA2 : depth >3 – 5 mm., diameter ≤ 7 mm.

– IB : clinical visible or greater than IA2• IB1 : visible ≤ 4 cm.• IB2 : visible > 4 cm.

• Stage II. extends beyond the cervix but has not extended onto the pelvic wall, involves the vagina < lower 1/3– IIA : No parametrium involvement,

upper 2/3 of vagina– IIB : With parametrium involvement

< pelvic sidewall

• Stage III. extended onto the pelvic sidewall and/or involves the lower 1/3 of the vagina, involve pelvic sidewall, hydronephrosis or nonfunctioning kidney– IIIA : No pelvic sidewall involvement,

lower 1/3 of vagina– IIIB : Extension to pelvic sidewall,

hydronephrosis or nonfunctioning kidney or regional lymph node metastasis

• Stage IV. extended beyond the true pelvis or has clinically involved the mucosa of the bladder and/or rectum– IVA : spread onto adjacent pelvic organs– IVB : spread to distant organs

Recommended Treatment

Preinvasive• Conization or loop electrosurgical

excisional procedure (LEEP) or laser or cryotherapy ablation or simple hysterectomy

Stage IA• Total abdominal hysterectomy or

trachelectomy or large cone biopsy with negative margins and close follow-up (if fertility preservation desired). Radical hysterectomy preferred for IA2 lesions

OR• Brachytherapy alone (LDR 65–75 Gy

or HDR 7 Gy × 5–6 fx). If high-risk pathologic features, treat as IB

Stage IB1• Radical hysterectomy with pelvic LN

dissectionOR• Definitive RT: EBRT to WP (45 Gy)

and brachytherapy (HDR 6 Gy × 5 fx, 7 Gy × 4 fx or LDR 15–20 Gy × 2 fx)

Stage IB2 - IIA• Concurrent chemo-RT with cisplatin.

WP RT (45 Gy). Brachytherapy = HDR 6 Gy × 5 fx, 7 Gy × 4 fx or LDR 15–20 Gy × 2 fx

Stage IIB• Concurrent chemo-RT with cisplatin.

WP RT (45–50.4 Gy). Brachytherapy = HDR 6 Gy × 5 fx, 7 Gy × 4 fx or LDR 15–20 Gy × 2 fx

Stage IIIA• Concurrent chemo-RT with cisplatin.

RT to WP, vagina, and inguinal LN (45 Gy-50.4 Gy). Brachytherapy = HDR 6 Gy × 5 fx, 7 Gy × 4 fx or LDR 17–20 Gy × 2 fx

Stage IIIB - IVA• Concurrent chemo-RT with cisplatin.

WP RT (50–54 Gy). Brachytherapy = HDR 6 Gy × 5, 7 Gy × 4 fx or LDR 20 Gy × 2. If LN+, add paraaortic LN IMRT (45–60 Gy)

Stage IVB• Combination chemotherapy

Indication for post-op RT

• Lymphovascular space invasion (LVSI)• Deep stromal invasion > one-third of

stromal depth• Tumor size > 4 cm• Adenosquamous, clear cell, small cell,

undifferentiated histology

Indication for post-op Chemo + RT• Surgical margin (+)• LN (+)• Parametrial involvement

Five-year survival in FIGO stage IB cervical cancer according to surgery or radiotherapy

EBRT

• CT-based planning is recommended• Intensity-modulated radiation

therapy (IMRT) should be considered experimental

Beam Energy and Dose Calculation• A megavoltage accelerator with a minimum source

to an isocenter distance of 100 cm is recommended.

• Higher energy photons beams, 10–18 MV, should be used if possible to reduce the dose to normal tissue.

• Doses are to be calculated without heterogeneity correction, i.e., no correction is to be made for density differences between air in the bowel and fluid in the bladder.

• Four fields should be used for maximal sparing of normal tissue (especially small bowel and sciatic nerve).

FieldAnterior–posterior fields• Superior : L4–L5 intervertebral

space• Inferior : below the obturator

foramens (vagina (−)) or ischial tuberosities (vagina (+))

• Lateral : bony pelvis +1.5–2 cm

Lateral fields• Superior and inferior: same as

anterior–posterior fields.• Anterior: posterior to pubis.• Posterior: between the S2 and

S3 vertebrae (midsacrum); maximum care should be given to posterior extension of tumor, and a margin of at least 1–2 cm should be given to the tumor.

Parametrial Boost field• indicated in patients with bulky primary disease.

An additional dose of 5.4–9.0 Gy can be considered for parametrial

• The superior border : 1 cm superior to the bottom of the SI joint.

• The lateral and inferior borders : are identical to the AP/PA field of the whole pelvic setting.

• A midline block of 4–5 cm in diameter blocks bladder and rectum hotspots from brachytherapy. A customized midline shielding can be contoured using a point A isodose line and is associated with fewer complications

• Paraaortic LN (+); paraaortic field should be irradiated

• Prophylactic paraaortic field is not recommended since it has no effect on survival. It also decreases the tolerance of radiotherapy by increasing toxicity

Paraaortic field

Paraaortic fieldAP/PA fields– superior border : T11 and T12 interspace– inferior border : L4–5 interspace (if separating

from pelvic fields) or continues with the AP/PA fields of the pelvic portal

– lateral border : lateral aspects of transverse processes

Lateral fields– anterior border : 2 cm anterior to vertebral

bodies– posterior border : should split the vertebral

bodies

Dose and Fractionation• The whole pelvic field should be treated to 45–50.4

Gy with conventional fractionation (1.8 Gy or 2.0 Gy per fraction)

• If the para-aortic fi eld is added, the para-aortic field should be treated with up to 45 Gy at 1.5–1.8 Gy per fraction

• Parametrial boost should be treated with 5.4–9.0 Gy at 1.8 Gy per fraction

• The approximate average total dose to point A with the LDR brachytherapy implant should deliver 35–45 Gy as described below.

Conformal RT Volumes

• CTV = tumor/tumor bed, entire uterus, upper one-third of vagina, parametrium, iliac

• LNs. Paraaortic/common iliac LN (+); paraaortic LN.

• PTV = CTV + 0.5–1 cm.

Brachytherapy• BT plays a very important role in the

treatment of gynecological cancers, particularly cervical cancers

• Intracavitary and interstitial BT techniques are used in cervical cancers

• For stage IA1 or selected cases of IA2 cervical cancer, intracavitary tandem and ovoid/ring brachytherapy alone can be sufficient treatment

Radionuclides used for brachytherapy applications

Source Loading Types in Brachytherapy• Manual afterloading: radioactive sources are

applied by long forceps from a certain distance behind a protective barrier. The patient treated with the radioactive sources should be isolated in hospital.

• Remote afterloading: the radioactive source is stored within a shielded computer-controlled machine. The machine has a remote controller, and the radioactive source passes through special tubes and applicators placed inside the patient.

ICRU 38• Dose and Volume Specifications for

Reporting Intracavitary Treatments in Gynecologic Malignancies

• Every application of BT should report five major issues1. technique2. total reference air KERMA (TRAK)3. reference volume4. reference points and doses 5. dose rate

Technique

• The radioactive source• number and length of sources• the type of applicator

Reference air KERMA of source

• KERMA = kinetic energy released in the medium

• the same units as absorbed dose (Gy)• used to define visible activity• defined as the dose given at a distance of

1 m of air by a source with an activity of 1 MBq in 1 h

• Its units are 1 μ/Gy m2 = 1 cGy/h cm2

• Its value is 0.0342 for Ir-192

Reference volume

• volume surrounded by the reference isodose• independent of technique• combined volume in the 60 Gy isodose curve of

external pelvic radiotherapy and intracavitary applications

• defined in three planes by combining reference isodoses ; dh: (height), dw: (width), dt: (thickness)

Reference points

• Bladder reference point• Rectum reference point• Bony reference points; lymphatic

trapezoid (Fletcher trapezoid)• Pelvic wall reference points

Dose rate

• the dose given per unit time– low dose rate (LDR), 0.4–2 Gy/h– medium dose rate (MDR), 2–12 Gy/h– high dose rate (HDR), >12 Gy/h

The advantages and disadvantages of HDR brachytherapy

Dose Prescription Points

• most commonly used ones are points A and B

Point A

• defined in the Manchester system2 cm superior to a horizontal line passing from the top of the lateral fornices at the midline and 2 cm lateral from the midline

• It is the point where radiation necrosis is first seen, and uterine artery crosses ureter

• relates to the maximum dose for healthy tissues and the minimum dose for the tumor

Point B

• This point is 3 cm lateral to point A• shows the dose taken by the obturator LNs

Isodose distribution

Application of Intracavitary Brachytherapy• the patient should be informed• gynecological exam• lithotomy position• vulva, perineum, and pelvic region are

cleaned• a Foley catheter is placed into the bladder

and its balloon is filled with 7 cc of radioopaque material

• speculum is placed into the vagina, and the cervical os is visualized

• metal markers are placed into the cervical os to verify the position of the intrauterine tandem

• the length of the uterine cavity is determined by hysterometry

• the tandem and ovoids are lubricated with 1% viscous lidocaine

• The tandem is first placed into the uterine cavity, and then the ovoids or ring are placed into the fornices and they are all stabilized

• vaginal packing• rectal tube is inserted into the rectum

• Dummy catheters are placed into the tandem and ring/or ovoids

• An A–P and a lat. film are taken at the same position

• The dose is prescribed to point A• The source, place and time are optimized in

dosimetry• Applicators are connected to the treatment

machine with special connecting cables• Health personnel move from the treatment

room to the command room and start the BT session

Tolerance doses

• Rectum, 75 Gy (mean 68 Gy, <80% of the dose at point A)

• Bladder, 80 Gy (mean 70 Gy, 85% of the dose at point A)

• Vagina, 120–140 Gy (mean 125 Gy)

ComplicationsAcute complications• pruritis, dry/moist desquamation• enteritis• proctitis• cystourethritisLate complications• Vaginal stenosis• Vaginal ulceration or necrosis• Late gastrointestinal complications• Ureteral stricture• vesicovaginal or rectovaginal fistula

Thank You.

References :• R. Scott Bermudez, Kim Huang, and I-Chow Hsu in Eric K. Hansen (2010). Cervical

Cancer. Handbook of Evidence-Based Radiation Oncology 2nd Edition : (29) 499-511

• Murat Beyzadeoglu, Cuneyt Ebruli, and Gokhan Ozyigit in Murat Beyzadeoglu .Basic Radiation Oncology (2010) . Gynecological Cancers . Cervical Cancer : (9) 411-432

• Subhakar Mutyala and Aaron H. Wolfson in J. J. Lu ・ L. W. Brady (Eds.) (2008) Gynaecological Cancers. Radiation Oncology An Evidence-Based Approach : (24) 358-368