New pregnancy, genetic testing guidance added to AAD’s melanoma guidelines
FROM THE JOURNAL OF THE AMERICAN ACADEMY OF DERMATOLOGY
In an interview, Dr. Swetter also said that is critical that the updated guidelines have been harmonized with changes made in the American Joint Committee on Cancer’s 8th edition of its melanoma staging manual. Key points for dermatologists to understand that reporting of Breslow thickness to the nearest 1/10th decimal point (over the nearest 1/100th), such that a melanoma measuring 0.75-0.84 mm in thickness would be reported as 0.8 mm depth and one between 0.95-1.04 mm would be rounded to 1 mm.
The main changes regarding staging of thin (T1) melanoma – that is less than or equal to 1 mm – is that the 0.8 mm thickness is the threshold for a T1a melanoma (now classified as less than 0.8 mm without ulceration), whereas T1b is now 0.8 – 1.0 mm thickness with or w/out ulceration or less than 0.8 mm thickness with ulceration. A T1a melanoma generally is not considered appropriate for staging of the regional lymph nodes with sentinel lymph node biopsy (with exceptions noted in the guideline), whereas a T1b melanoma may be considered for SLNB staging – though rates of SLN positivity remain relatively low in the T1b group.”
Dr. Swetter also emphasized that histologic ulceration of the primary tumor was affirmed as an indicator of worse prognosis; mitotic rate, although removed from T1 staging, is still tracked by pathologists and still seen as an independent predictor of worse prognosis, according to the 8th edition, she said.
A cornerstone of cutaneous melanoma care remains unchanged in the guidelines: Surgical excision is still the preferred method for treating melanoma. “Mohs micrographic surgery and other staged excision techniques can provide exhaustive peripheral margin histologic assessment for melanoma in situ, lentigo maligna type and tissue sparing in anatomically constrained sites,” Dr. Swetter said. “Current data are insufficient to recommend Mohs surgery for invasive cutaneous melanoma, in which the use of surgical margins less than 1 cm has not been adequately studied,” she cautioned.
Reinforcing the importance of surgery as the primary treatment for melanoma, Dr. Swetter clarified that “Nonsurgical approaches (imiquimod and traditional forms of radiation therapy) should be considered [only] if surgery is impractical or contraindicated, and only for melanoma in situ, lentigo maligna type, as cure rates are lower.”
In terms of other therapies, the guideline working group found insufficient evidence to recommend electronic brachytherapy for melanoma.
Assessment of novel diagnostic and molecular imaging modalities was not the primary focus of the AAD guidelines, Dr. Swetter pointed out. Looking to the future, though, she added that the hope is “that these prebiopsy modalities can one day reduce unnecessary biopsies from being done” in the clinic.
Other knowledge gaps cited by the working group included several related to pathology, including determination of appropriate margin control in some lesion types, and the quest to reduce inter-reader variability in histopathologic diagnosis of melanocytic tissue samples. However, noted Dr. Swetter and her coauthors, the rapid pace of genomic medicine advances “may make many of the aforementioned issues obsolete” before the next guideline update.
In the interview, Dr. Swetter said that the guidelines reflect evolving thinking about melanoma in the context of a rapidly growing field. “Only in the last year have effective, more tolerable adjuvant therapies been [Food and Drug Administration] approved for patients with resected stage III melanoma, including patients with regional lymph node disease detected via sentinel lymph node biopsy. The hope is that less invasive procedures for melanoma will be performed in the future, and replaced by better drugs and novel techniques.”
Dr. Swetter reported that she had no relevant financial disclosures; several working group members reported multiple financial relationships with pharmaceutical, diagnostic, and imaging companies. Working group members were recused from discussion of guidelines where their particular relationships might pose a conflict of interest.
SOURCE: Swetter S. et al. J Am Acad Dermatol. 2011 Nov;65(5):1032-47.
