Delayed postoperative radiation tied to higher recurrence, death in MCC

Delays in postoperative radiation therapy (PORT) may lead to increased locoregional recurrence (LRR), usually occurring beyond the radiation field, among patients with Merkel cell carcinoma (MCC), as shown in a recent study.

“This is consistent with the tendency of MCC to spread quickly via lymphatics,” the authors said.

On the other hand, early initiation of PORT (ie, within 8 weeks) results in better locoregional control and MCC-specific survival.

To determine whether delays in time to PORT contributed to worse outcomes, the authors used competing risk regression and explored the associations between time to PORT and LRR for patients with stage I/II MCC in a prospective registry. Distant metastasis and death served as competing risks.

A total of 124 patients with a median time to PORT of 41 days (range, 8‒125) were included in the analysis. Over a median follow-up of 55 months, 17 patients (14 percent) had an LRR, of which 14 (82 percent) stemmed from outside the radiation field.

LRR at 5 years was markedly higher for time to PORT >8 weeks compared to ≤8 weeks (28.0 percent vs 9.2 percent; p=0.006). In addition, the cumulative incidence of MCC-specific death increased the longer delay in PORT was (hazard ratio per 1-week delay, 1.14; p=0.016).

This study was limited by the relatively low number of LRRs, according to the authors.