Radiation Oncology/Vagina/Overview

Vaginal Cancer Overview

Epidemiology

• Majority of vaginal neoplasms are metastatic; typically by direct extension (vulva/cervix), lymphatics, or hematogenous spread.
• According to FIGO staging, if the tumor involves vulva or the cervical os, it is classified as arising from that structure, even if it is centered in vagina
• Only 10-20% are primary vaginal tumors, and account for ~2% of gynecologic malignancies
• Age:
  • 75% in patients >50
  • 60% in patients >70
• Location PMID 5162136 (1971):
  • 58% tumors occur on posterior wall
  • 51% tumors occur in upper 1/3 of vagina
• Approximately 60% have had prior hysterectomy for variety of reasons

Anatomy

Vaginal Anatomy

• Introitus - vaginal opening
• Hymen - thin tissue membrane concealing vaginal canal. Formed by connection of the urogenital sinus epithelium invaginating inward, with the mullerian ducts descending from above
• Fornices - invaginations between walls of vagina and cervix
• Pouch of Douglas - retrouterine pouch separating vagina from rectum
• Average length 7.5 cm
• Vaginal wall
  • Stratified squamous epithelium
  • Muscularis layer
  • Adventitia

Lymphatic drainage of vagina

• Complex
• Upper 2/3 of vagina - pelvic nodes (obturator, internal/external iliac)
• Lower 1/3 of vagina - inguinal and pelvic nodes
• 5-20% present with clinically positive nodes

• Torino, Italy; 2002 PMID 12210022 -- "Rationale and definition of the lateral extension of the inguinal lymphadenectomy for vulvar cancer derived from an embryological and anatomical study." (Micheletti L, J Surg Oncol. 2002 Sep;81(1):19-24.)
  • Embryological and anatomic study to determine lateral extension of groin lymphadenectomy in vulvar cancer. 3 human fetuses, 1 patient dissected
  • Outcome: Most lateral superficial inguinal lymph node does not rise above medial margin of the sartorius muscle, nor far lateral to where superficial circumflex iliac vessels cross the inguinal ligament
  • Conclusion: Lateral surgical landmark established

Risk Factors

• Approximately 2/3 are HPV-related
• HSV, trichomonas, number of sexual partners >5
• Long term pessary use, smoking, immunosuppression, pelvic radiation
• Maternal use of diethylstilbestrol (DES) during first 4 months in utero

Associated with prior cervical carcinoma

• U. Michigan, 1982 - PMID 7095583 (No abstract) PDF -- "Neoplasms of the vagina following cervical carcinoma." (Choo YC, Gynecol Oncol. 1982 Aug;14(1):125-32.)

Prevention & Screening

• Insufficient evidence for women s/p TAH
• Pap smear for high-risk populations; continue into older years

Presentation

• Abnormal vaginal bleeding in 50-75%, discharge, pruritus
• Dysuria, pelvic pain in more advanced disease

Work-Up

• Speculum examination, rotate to observe posterior wall
• Vaginal palpation, bimanual pelvic, rectovaginal for staging
• Evaluate vulva and cervical os for disease - biopsy suspicious lesions
• Evaluate for mets with CXR, CBC, LFTs and alk phos
• Biopsy suspicious inguinal nodes
• Stage II or greater consider cystoscopy and/or sigmoidoscopy
• Consider MRI - superior to CT for evaluation of soft tissue extension (though neither may be used in clinical staging)
  • Consider dynamic contrast MRI

• Manchester; 2007 (UK)(1996-2005) PMID 17467392 -- "Magnetic resonance imaging of primary vaginal carcinoma." (Taylor MB, Clin Radiol. 2007 Jun;62(6):549-55.)
  • Retrospective. 25 patients with MRI examination. Isointense to muscle on T1, hyperintense on T2
  • Outcome: 88% extension beyond vagina, 56% Stage III/IV
  • Conclusion: MRI identified >95% tumors, radiological staging correlated with outcome, and provided treatment planning information

Histology

• Squamous cell carcinoma (80-90%), primarily in older patients, invade locally with mets to lung and liver
• Melanoma (3-5%), second most common cancer in vagina
• Clear cell carcinoma, particularly in young women with DES exposure in utero (FDA advised against DES use in 1971 - thus incidence has dropped dramatically)
• Rhabdomyosarcoma (botryoid type) most common in children
• Verrucous carcinoma (rare) - tend to recur locally and rarely metastasize thus surgical approaches may be appropriate PMID 635607

Prognostic Factors

• Clinical stage most important
• Adenocarcinoma and non-epithelial tumors (melanoma, sarcoma) worse than squamous cell