Local Recurrence After Excision of Merkel Cell Carcinoma

Society of Cutaneous Oncology

2026-06-12

SoCO Journal Club · June 12, 2026

Local recurrence after excision of Merkel cell carcinoma

A discussion about what the baseline risk of true primary-site local recurrence actually is, how postoperative radiation changes that risk, and how much certainty we need before exposing every patient to additional treatment.

Meeting pulse

A large MCC group — and a long discussion

People who joined

Unique cleaned people in the Teams attendance record

Median time together

94 min

Half the group stayed at least this long

Stayed at least an hour

76%

Joined for at least 60 minutes

Participation

A few ways people participated

Teams captures only a few coarse signals, but they give a useful sense of how actively the group engaged with a nearly two-hour discussion.

Camera on

68%

Had the camera on at least once

Unmuted

59%

Unmuted at least once during the meeting

Raised a hand

21%

Used the Teams hand-raise signal

The paper we discussed

Kavanagh et al. — local recurrence after complete excision

Primary article · Annals of Surgical Oncology

Local Recurrence Following Complete Surgical Excision of Primary Merkel Cell Carcinoma

Kavanagh FG, et al. Ann Surg Oncol. 2026;33(7):6681–6690.
doi: 10.1245/s10434-025-18670-2

PubMed DOI

The question beneath the paper: After a negative-margin excision, how much risk of true primary-site local recurrence remains — and when is postoperative radiation worth using to prevent it?

The study examined 447 patients with clinically localized MCC treated at Memorial Sloan Kettering Cancer Center. Among 393 patients treated with negative-margin surgery alone, seven local recurrences occurred within the first year, corresponding to an estimated 1-year local recurrence rate of 1.8%. The rarity of the event also meant that conventional risk-factor modeling was inherently difficult.

An important interpretive issue: this was a natural-history study, not a randomized comparison of surgery versus postoperative radiation. Patients selected for radiation differed from those treated with surgery alone, so the study is highly informative about observed local recurrence after surgery but cannot by itself estimate the causal effect of radiation.

Before the discussion

The survey showed why this question is still unsettled

The Journal Club survey, later incorporated into the SoCO Perspectives on the Science article, made the practice variation visible before the group debated the paper. Clinicians were not starting from a shared estimate of baseline risk or a shared threshold for postoperative radiation.

6–10% Most common baseline estimate

Before the session, the largest group of respondents estimated local recurrence after margin-negative excision alone at 6–10%, even though estimates ranged from below 2% to above 10%.

44% Individualized RT

The largest group reported individualizing postoperative RT according to patient- and tumor-specific risk factors; 20% routinely recommended RT for nearly all patients and 20% rarely recommended it.

Prospective data Most likely to change practice

A prospective registry or clinical trial was the evidence type respondents most often selected as most likely to change current practice.

The survey also showed that disagreement extends beyond whether to radiate. Respondents varied in preferred dose and fractionation, and the clinical scenarios revealed broad agreement at the lowest- and highest-risk extremes but substantially more variation in intermediate and preference-sensitive situations.

Discussion highlights

What stuck with us from the conversation

The debate quickly moved beyond the point estimate. The group spent most of its time on what constitutes a true local recurrence, whether existing “high-risk” features actually predict that event, how salvage changes the clinical meaning of recurrence, and what kind of study could finally move the field.

01 · Define the event

“High risk” is not necessarily high risk for local recurrence

Dan Coit emphasized that many features used to guide postoperative radiation were originally linked to nodal disease, recurrence broadly, disease-specific survival, or overall survival — not specifically to primary-site local recurrence. The endpoint has to match the treatment question.

02 · The baseline risk

The number everyone needs — and still disagrees about

The MSK cohort places observed 1-year local recurrence after surgery alone at 1.8%. But the group debated whether treatment selection means the untreated risk in a broader population could be meaningfully higher. The argument was not simply about statistics; the baseline risk drives the absolute benefit radiation can plausibly provide.

03 · Salvage matters

Preventing an event depends on what happens if the event occurs

Dan pushed the group to consider local recurrence together with salvage. If true local recurrence is uncommon and usually controllable with surgery and/or radiation after it occurs, the value of routinely treating everyone up front changes substantially.

04 · Treatment burden

Neither surgery nor radiation is one thing

Paul Nghiem emphasized that wider surgery can carry meaningful morbidity, particularly in the head and neck, while contemporary radiation can sometimes be delivered with substantially less burden than historical courses. The real comparison is not “treatment versus no treatment,” but the absolute benefits and harms of specific strategies.

05 · Equipoise

We may be radiating too many patients — but we still do not know whom to omit

Vern Sondak captured the tension well: he worried that current practice may overtreat many patients, yet remained uncertain about which patients can safely avoid radiation. That uncertainty is exactly what makes prospective evidence generation necessary.

06 · The next study

Better data need a better inferential framework

The discussion moved toward multicenter data, explicit causal assumptions, absolute risk estimation, and Bayesian approaches that can represent uncertainty directly. In a rare disease with a rare endpoint, a future study has to ask a decision-relevant question rather than simply search for statistically significant predictors.

The practical question is not simply whether radiation reduces local recurrence. It is: for this patient, how much absolute local-recurrence risk is being prevented, what happens if recurrence occurs, and what burden are we accepting to prevent it?

Where the discussion landed

The meeting did not end with consensus — and that was useful.

The Kavanagh study provides unusually direct evidence that true primary-site local recurrence can be uncommon after complete negative-margin excision. At the same time, selection into postoperative radiation, variation in surgical and radiation strategies, and disagreement about the baseline untreated risk prevent the study from resolving the causal treatment question on its own.

The group converged more clearly on what the next evidence should look like: better-defined endpoints, curated multicenter data, explicit attention to salvage and treatment burden, and analyses that estimate absolute treatment benefit under uncertainty.

From Journal Club to Perspectives

The discussion became a paper

Perspectives on the Science · Journal of Cutaneous Oncology