Radiotherapy influences local control in patients with desmoplastic melanoma

Abstract

BACKGROUND Desmoplastic melanoma may have a high risk of local recurrence after wide excision. The authors hypothesized that adjuvant radiotherapy (RT) would improve local control in patients with desmoplastic melanoma, resulting in at least a 10% absolute decrease in local recurrence rate. METHODS A total of 277 patients from 1989 through 2010 who were treated for nonmetastatic desmoplastic melanoma by surgery with or without adjuvant RT were reviewed. Clinicopathologic and treatment variables were assessed with regard to their role in local control. RESULTS A total of 113 patients (40.8%) received adjuvant RT. After a median follow-up of 43.1 months, adjuvant RT was found to be independently associated with improved local control on multivariable analysis (hazards ratio, 0.15; 95% confidence interval, 0.06-0.39 [P <.001]). Among 35 patients with positive resection margins, 14% who received RT developed a local recurrence versus 54% who did not (P =.004). In patients with negative resection margins, there was a trend (P =.09) toward improved local control with RT. In patients with negative resection margins and traditionally high-risk features, including a head and neck tumor location, a Breslow depth > 4 mm, or a Clark level V tumor, RT was found to significantly improve local control (P <.05). The data from the current study would suggest that patients who would be good candidates for omitting RT included those with negative resection margins, a Breslow depth ≤4 mm, and either no perineural invasion present or a non-head and neck tumor location. CONCLUSIONS RT for desmoplastic melanoma was independently associated with improved local control. Patients with positive resection margins or deeper tumors appeared to benefit the most from RT, whereas selected low-risk patients can safely omit RT.

Results of NCCTG N0275 (Alliance) – a phase II trial evaluating resection followed by adjuvant radiation therapy for patients with desmoplastic melanoma

“…That being said, given our prospective data, as well as several retrospective reports, adjuvant RT should be considered for all patients with DM after margin‐negative WLE 8, 15, 25, 29. As noted above, there are selected DM patients who can potentially have adjuvant RT omitted as part of their treatment plan, though additional study is needed to further refine and define these low‐risk patient populations.…”

“…Historical local recurrence rates (LRRs) for patients with DM are in the range of 20–50% 2, 3, 4, 5, 7, 8, though recent series have suggested potentially lower rates in selected patients (negative margins, non‐head and neck location, lack of perineural invasion, decreasing Breslow depth, etc.) 9, 10, 11, 12. This is in contrast to patients with other cutaneous melanomas who have LRRs of 1–13%, depending on tumor depth and the presence or absence of ulceration 13, 14, 15.…”

“…15 at Moffitt Cancer Center examined the role of RT in patients with DM. A total of 277 patients with nonmetastatic DM were treated between 1989 and 2010.…”

“…This certainly argues for re‐resection whenever feasible/tolerable in order to achieve negative margins. Of importance, the authors did identify two low‐risk groups in their analysis who could potentially omit adjuvant RT: (1) patients with negative margins, a non‐head and neck tumor location, and a Breslow depth ≤4 mm; and (2) patients with negative margins, a Breslow depth ≤4 mm, and no perineural invasion 15. Other authors have also noted patient populations at low risk for a LR who could potentially omit adjuvant RT 9, 10, 12.…”

“…9, 10, 11, 12. This is in contrast to patients with other cutaneous melanomas who have LRRs of 1–13%, depending on tumor depth and the presence or absence of ulceration 13, 14, 15. Higher rates of recurrence in DM patients have generally been attributed to the failure to adequately excise clinically occult projections of tumor 5, though many other tumor‐ and treatment‐related factors may play a role in LRRs (size of surgical margins, extent of desmoplasia, Breslow thickness, Clark level, head and neck location, neurotropism, etc.…”