PHOENIX Although cutting through a melanoma during a shave biopsy may make reaching an accurate prognosis more difficult, it probably will not harm the patient, Dr. Darrell Rigel said at a clinical dermatology conference sponsored by Medicis.
Dr. Rigel, who is with New York University Medical Center, New York, said that two recently published studies addressed the concern that cutting through certain cancers during a biopsy can disperse tumor cells and worsen prognosis. It probably is not harmful in melanoma patients, he said.
The studies he cited compared excisional with incisional biopsies.
In the first study, investigators from Carolinas Medical Center in Charlotte, N.C., reported that 22% of shave biopsies had positive deep margins (Ann. Surg. Oncol. 2007;14:89398). In the second study, investigators from the Free University Hospital, Amsterdam, found that use of incisional biopsies did not have a negative impact on survival (Ann. Surg. Oncol. 2007;14:142430).
"So at least if you accidentally shave through a melanoma, you [probably] haven't harmed the patient," Dr. Rigel said. "However, you may have harmed your ability to get the right prognosis for the patient." Thinner melanomas have a better prognosis, he noted, but tumor thickness is harder to determine in patients with deep positive margins.
In the first study, Dr. Richard L. White Jr. and his colleagues analyzed pathology reports from Jan. 1, 2004, through June 30, 2005, for 223 cases of primary melanoma.
Although the National Comprehensive Cancer Network and the American Academy of Dermatology have each designated excisional biopsies with narrow margins as the preferred method for diagnosing primary cutaneous melanoma, more than half the biopsies were done with the easier, faster shave technique. The sample comprised 51 excisional biopsies, 44 punch biopsies, and 128 shave biopsies. Three-fourths (167) of the specimens analyzed were from thin melanomas (1 mm or less).
Only 16% of excisional biopsies had positive margins. Just 2% were positive deep margins, and none were found in specimens from the thin melanomas.
Punch biopsy specimens also had no positive deep margins in the thinner melanomas. Positive margins were more common overall (68%), but were mostly wide margins attributable to the punch technique. Only 7% of all punch biopsies had positive deep margins.
Half of all shave biopsies produced positive margins, including the 22% that had positive deep margins. The analysis revealed positive deep margins for 17% of the thinner melanomas sampled by the shave technique.
Shave biopsy was most commonly done for thinner melanomas. It also produced samples that were significantly thinner. A review of 56 specimens showed the average biopsy thickness to be 1.41 mm with the shave technique, 3.58 mm with the punch method, and 3.19 mm for excisional biopsies.
"Based on these data," the authors concluded, "we encourage the use of an excisional biopsy technique for all skin lesions where melanoma is in the differential diagnosis when excision is feasible."
In the second study, Dr. Paul A.M. van Leeuwen and his colleagues in the Netherlands prospectively studied 471 patients who were diagnosed with stage I or II melanoma after partial removal of a skin lesion. Most of the patients had a superficial spreading melanoma (65%) or a nodular melanoma (26.7%). Average follow-up was 5 years or more.
The investigators divided the population by biopsy type: wide excision biopsy (279 patients), narrow excision biopsy (109), excision biopsy with positive margins (52), and incision biopsy (31). Biopsy type did not prove to be significant in univariate or multivariate analyses of disease-free survival or overall survival. The presence of residual tumor cells in reexcision specimens for 41 patients also was not significant.
"Incisional biopsies are not recommended, but there is no cause for concern when an excision biopsy turns out to have positive margins," the authors concluded.
In a telephone interview, Dr. Randall K. Roenigk agreed that both studies make good points, but he said that they are not likely to dissuade physicians from doing shave biopsies.
"If you do a shave and miss the depth of the specimen, you miss a key bit of informationthe thickness of the melanoma. Your decision-making tree could be compromised," said Dr. Roenigk, professor of dermatology and chair of the department of dermatology at Mayo Medical School, Rochester, Minn.
"On the flip side, it is easier to do a shave biopsy," he continued, citing the time required for an excisional biopsy, the delay in diagnosis until an excisional biopsy can be scheduled, and the reality that some patients won't come back for the procedure.
He suggested that, as a result, doing more shave biopsies can mean more melanoma diagnoses, even though excisional biopsies are more comprehensive. From Dr. Roenigk's perspective, the studies demonstrate the importance of doing deep biopsies even when the suspected melanoma appears to be thin.