Radiation Oncology: A Question-Based Review

Vaginal Cancer

Boris Hristov and Lilie Lin

image Background

Vaginal cancer typically presents in what age group?

70% of primary vaginal malignancies are detected in women ≥60 yo.

What 3 lifestyle risk factors are associated with increased incidence of vaginal cancer?

Increased risk of vaginal cancer is associated with the # of lifetime sexual partners, early onset of intercourse, and current smoking.

What % of cancers involving the vagina are not primary vaginal cancers?

~75% of malignancies involving the vagina originate at other sites.

What is the most common histology for vaginal cancer? What are 5 other rare vaginal cancer histologies?

Squamous cell carcinoma is the most common primary vaginal histology. Melanoma, sarcoma, lymphoma, adenocarcinoma, and clear cell adenocarcinoma are much more rare.

Increased risk for clear cell adenocarcinoma is linked with what exposure?

In utero exposure to the synthetic estrogen diethylstilbestrol (DES) is linked with an increased risk for clear cell adenocarcinoma.

What type of vaginal sarcoma is most common in adults? In children?

1.     Adults: leiomyosarcoma

2.     Children (<6 yo): embryonal rhabdomyosarcoma (i.e., sarcoma botryoides)

If an elderly woman has had a hysterectomy due to early-stage cervical cancer, is it reasonable to continue PAP smear screening of the vaginal vault?

Yes. Though the value of continued screening is not proven, PAP smears of the vaginal vault in elderly women who have had hysterectomy for invasive/preinvasive cervical cancer seems reasonable given the increased risk for vaginal cancer.

What is the nodal drainage of the upper two thirds of the vagina? Of the lower one third of the vagina?

The upper two thirds of the vagina drains to the obturator, internal, external, and common iliac nodes. The lower one third of the vagina may drain to the inguinofemoral nodes.

What are 4 common presenting Sx of vaginal cancer? What 2 additional Sx may suggest locally advanced Dz?

Vaginal cancer may present with bleeding, discharge, pruritis, and dyspareuniaPain or change in bowel/bladder habits may suggest locally advanced Dz.

Where in the vagina is vaginal cancer most often located?

Vaginal cancer is most often found in the post wall, sup one third of the vagina (the speculum must be rotated to ensure exam of this region).

image Workup/Staging

What staging exams/studies contribute to the FIGO stage?

Exams/studies that contribute to the FIGO stage include clinical exam of the pelvis and vagina (possibly under anesthesia), cystoscopy and proctosigmoidoscopy in women with locally advanced Dz, CXR, LFTs, and alk phos.

What imaging studies do not contribute to the FIGO stage?

Advanced imaging such as CT, MRI, and PET do not contribute to the FIGO stage (but still should be used to assess the Dz extent and plan therapy).

What is the FIGO (2008) staging for vaginal cancer?

1.     Stage 0: CIS

2.     Stage I: tumor limited to vaginal wall

3.     Stage II: tumor invades paravaginal tissue but not pelvic sidewall

4.     Stage III: tumor extends to pelvic sidewall

5.     Stage IVA: tumor invades mucosa of bladder/rectum (bullous edema alone is not sufficient) and/or directly extends outside pelvis

6.     Stage IVB: DMs

A vaginal cancer is never considered a vaginal primary if it involves either of what 2 structures?

Cancer involving the vulva or cervix is never considered to be a vaginal primary (even if the bulk of Dz lies in the vagina).

When working up a presumed vaginal cancer primary, what other 3 sites should be evaluated for cosynchronous in situ or invasive Dz?

When working up a presumed vaginal cancer primary, always evaluate for cosynchronous cervical, vulvar, and/or anal Dz.

image Treatment/Prognosis

What are 3 appropriate Tx for vaginal intra-epithelial neoplasia (VAIN)?

Surgical excision, laser vaporization, and topical 5-FU are all appropriate Tx for VAIN.

VAIN is multifocal in what % of pts?

Up to 60% of pts with VAIN have multifocal Dz. Close follow-up is essential.

In general, what is the preferred definitive Tx modality for vaginal cancer?

Although surgery may be appropriate for early, stage I lesions, definitive RT is generally the preferred Tx modality (as morbidity is less compared with radical surgery).

What are the estimates of 5-yr pelvic Dz control and DSS for stage I, II, and III–IVA vaginal cancer managed with definitive RT?

For vaginal cancer managed with definitive RT, 5-yr pelvic Dz control is 86%, 84%, and 71% for FIGO stage I, II, and III–IVA, respectively. 5-yr DSS is 85%, 78%, and 58%, respectively. (Frank SJ et al., IJROBP 2005)

Is concurrent CRT a reasonable consideration in advanced-stage vaginal cancer?

Yes. Extrapolating from the cervical, vulvar, and anal cancer literature, concurrent CRT (typically cisplatin based) is reasonable to consider for advanced-stage vaginal cancer (i.e., stages III–IVA).

Is vaginal cylinder brachytherapy alone (without EBRT) appropriate in any vaginal cancer pts?

Possibly. While whole pelvis EBRT combined with brachytherapy is generally preferred, vaginal cylinder brachytherapy alone may be acceptable for pts with VAIN or very early stage I vaginal cancer <5 mm thick.

What brachytherapy technique is commonly required for stage II–III vaginal cancer (in addition to EBRT Tx)?

Interstitial brachytherapy needle implants are commonly required to achieve adequate brachytherapy dose coverage for stage II–III vaginal cancers (the depth-dose characteristics of intracavitary applicators are not favorable enough to treat deep lesions).

What are the typical field borders for vaginal cancer whole pelvis fields?

Typical whole pelvis vaginal cancer field borders:

1.     Top: L5-S1

2.     Bottom: entire vagina or 3 cm below Dz extent

3.     Lateral: 2 cm beyond pelvic brim

If the lower 3rd of the vagina is involved, then treat inguinal nodes as well (as per vulvar or anal cancer).

What are the appropriate EB and cumulative (EB + brachytherapy) RT doses for vaginal cancer?

Whole pelvis (+/− inguinal nodes) EB doses are typically 45–50 Gy → brachytherapy boost to a total dose of 70–80 Gy.

Among pts who fail following definitive RT, what % have LR as a component of their relapse?

~75% of pts with relapse following definitive RT for vaginal cancer will experience LF. (Frank SJ et al., IJROBP 2005)

image Toxicity

What are the 5- and 10-yr grade 3–4 toxicity rates following definitive RT for vaginal cancer?

Grade 3–4 toxicity rates are 10% and 17% at 5 and 10 yrs, respectively, following RT for vaginal cancer. (Frank SJ et al., IJROBP 2005)

What are the 4 most common grade 3–4 late effects following definitive RT for vaginal cancer?

Following definitive RT for vaginal cancer, proctitis (requiring transfusion), rectal fistula, SBO, and hemorrhagic cystitis are the most common grade 3–4 toxicities.

What common late effect may limit sexual function as well as follow-up for vaginal cancer?

Vaginal stenosis is very common following RT for vaginal cancer. All pts should use a vaginal dilator.