Commentary (Burke): Melanomas of the Vulva and Vagina

Dr. Trimble's review of female genital tract melanomas provides a well-organized summary of the published information on these rare cancers. His inclusion of the two recent population-based samples from the United States and Sweden [1,2] is particularly useful because all of the available data on genital tract melanomas comes from long-term retrospective case reviews. The cited incidence rates calculated in the studies represent the first legitimate estimates of the incidence of these uncommon cancers.

As is frequently the case in women with squamous vulvovaginal cancers, delays in the diagnosis of lower genital tract melanomas are relatively common. Despite efforts to encourage self-examination and to train physicians to biopsy all pigmented genital lesions, we find that these methods of asymptomatic early diagnosis are unusual. Most women are symptomatic at presentation. Patients who present with a mass, pain, or bleeding tend to have large local lesions with significant potential for lymph node and systemic dissemination. It is also important to emphasize the need for either excisional or full-thickness punch biopsy of suspicious lesions so that an accurate assessment of tumor thickness and depth of invasion can be obtained.

Unfortunately, the rarity of these lesions hampers a detailed assessment of prognosis. Nevertheless, Dr. Trimble has provided a very complete discussion of both macrostaging and microstaging systems. There seems to be a general consensus that the American Joint Committee on Cancer (AJCC) and Chung systems are the most useful in predicting outcome. For vulvar lesions, central (as opposed to lateral) location seems to signal a poorer prognosis [3]--perhaps because these tumors have a more complex lymphatic drainage pattern that provides access to both inguinal and deep pelvic nodes. The extremely poor prognosis observed in women with vaginal melanomas probably results from a combination of late onset of symptoms, presence of bulky disease at diagnosis, and central location.

Trends, Controversies in Treatment

As Dr. Trimble notes, the trend in the surgical therapy of primary disease has been away from radical vulvectomy and exenteration and toward radical wide local excision. This treatment philosophy is certainly supported by the large body of evidence from surgical resection of nongenital cutaneous melanomas, which has defined resection margins of 1 cm for lesions less than 1 mm thick and 2 cm for intermediate-depth tumors. In Dr. Trimble's article, I would have preferred to see the results of surgical therapy for genital melanomas coalesced into table form for easier comparison.

The management of regional groin nodes in women with vulvovaginal melanomas is controversial. Options include no resection, superficial and/or deep dissection for prognostic purposes, and therapeutic resection of positive nodes. Surgical treatment of the groin is probably best individualized based on the size and depth of the primary tumor and the findings of clinical examination.

We are currently working to define more precisely the lymphatic drainage patterns of all vulvar malignancies using intraoperative lymphatic mapping to identify the sentinel node [4, 5]. Although there are minimal data on genital melanomas, Morton's group has published extensively on the reliability of sentinel node identification in patients with cutaneous melanomas [6]. Their observed false-negative rate was less than 1%. Use of sentinel node status to guide decisions regarding the extent of nodal dissection is an enticing concept that, unfortunately, will require substantial additional data before it can be routinely recommended for genital melanomas.

Role of Adjuvant Therapies

Dr. Trimble outlines the systemic adjuvant therapy trials conducted for patients with cutaneous lesions and appropriately suggests that patients with genital tumors might be entered on such studies. I agree that genital melanomas are so uncommon that independent trials for these sites are not possible.

The article does not address the adjuvant potential of external-beam irradiation to enhance local and regional control. While scant data have been reported [7,8], we often employ external-beam irradiation as an adjunct to surgical resection at both the primary site and the groin in women with large lesions or positive nodes. It is our clinical impression that such therapy reduces or delays local failure. It is unclear whether such treatment provides any survival benefit, but this appears unlikely because of the high rate of distant failure.

Combined therapy may also be an effective palliative alternative to exenterative resection for patients with very large tumors. Pending the identification of effective salvage therapy, women who develop distant failure are best entered into appropriate clinical trials.

References:

1. Weinstock MA: Malignant melanoma of the vulva and vagina inthe United States: Patterns of incidence and population-basedestimates of survival. Am J Obstet Gynecol 171:1225-1230,1994.

2. Ragnarsson-Olding B, Johansson H, Rutqvist LE, et al: Malignantmelanoma of the vulva and vagina. Cancer 71:1893-1897,1993.

3. Phillips GL, Bunday BN, Okagaki T, et al: Malignant melanomaof the vulva treated by radical hemivulvectomy: A prospectivestudy of the GOG. Cancer 73:2626-2632, 1994.

4. Levenback C, Burke TW, Gershenson DM, et al: Intraoperativelymphatic mapping for vulvar cancer. Obstet Gynecol 84:163-167,1994.

5. Levenback C, Burke TW, Morris M, et al: Potential applicationsof intraoperative lymphatic mapping in vulvar cancer. GynecolOncol 59:221-225, 1995.

6. Morton DL, Wen DR, Wong JH, et al: Technical details of intraoperativelymphatic mapping for early stage melanoma. Arch Surg 127:392-399,1992.

7. Harwood AR, Cummings BJ: Radiotherapy for mucosal melanomas.Int J Radiat Oncol Biol Phys 8:1121-1125, 1982.

8. Ross MI, Stern SJ, Wanebo HJ: Mucosal melanomas, in Balch CM,Houghton AN, Milton GW, et al (eds): Cutaneous Melanoma,pp 325-335. Philadelphia, JB Lippincott, 1992.