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Merkel Cell Carcinoma: Improved Outcome With the Addition of Adjuvant Therapy

Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, CT

To the Editor:

We read with interest the paper by Allen et al regarding the prognosis and treatment of patients with Merkel cell carcinoma.¹ The authors should be congratulated for their effort and detail in evaluating a single institution series of patients with Merkel cell carcinoma. The series reports on patients who were treated over a 32-year span with a mean follow-up of 46 months for those alive at last follow-up. The utility of adjuvant radiotherapy has been a topic that has been debated and this series appears to provide due diligence to the subject. Table 4 reveals that a total of 160 patients had received radiotherapy to the primary site and 25 patients had not. All 185 patients had negative margins following surgical management of their primary lesion. The crude local recurrence rates for the radiotherapy group versus the nonradiotherapy groups were 8% and 14%, respectively. The P value provided regarding this comparison is P = .45. It is possible given the relatively small number of patients who did not receive radiotherapy that the series may be underpowered to reveal a significant difference.² More critical is the crude reporting of local failures. For example, if the group of patients receiving radiotherapy was on average followed for 10 years, but the group of patients who did not receive radiotherapy was followed on average for only 5 years, then it is possible that additional failures in the nonradiotherapy arm might be recognized if followed for a comparable time period. In addition, no detail is provided regarding the equality of the group of patients who received radiotherapy versus the group of patients who did not other than the negative margin status. These issues would be easily addressed using an adjusted proportional hazards model, which would offer the medical community a stronger foundation on which to base therapeutic decisions regarding radiotherapy.

The data in Table 4 do not correspond to the information provided within the text. The text states that 41 patients received radiotherapy. This may be explained by mislabled columns in Tables 4 and 5. If this is the case, the same arguments should still apply. If the recurrence rate is 14% for those who received radiotherapy, and 8% for those who did not, then the arguments are less compelling.

Radiotherapy is not evaluated as a variable in association with disease-specific survival. Given that its use did not appear to affect local control through the crude reporting method, this is understandable. Should an adjusted proportional hazards model accounting for length of follow-up in both the adjuvant and no adjuvant radiotherapy groups disclose a significant difference in local control, it might be of interest to evaluate radiotherapy as a predictor of disease-specific survival.

Authors' Disclosures of Potential Conflicts of Interest

The authors indicated no potential conflicts of interest.

REFERENCES

1. Allen PJ, Browne WB, Jaques DP, et al: Merkel cell carcinoma: Prognosis and treatment of patients from a single institution. J Clin Oncol 23:2300-2309, 2005[Abstract/Free Full Text]

2. Wilson LD, Gruber SB: Merkel cell carcinoma and the controversial role of adjuvant radiation therapy: Clinical choices in the absence of statistical evidence. J Am Acad Dermatol 50:435-437, 2004[CrossRef][Medline]

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This Article Full Text (PDF) Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Services Email this article to a colleague Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Save to my personal folders Download to citation manager Rights & Permissions Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Wilson, L. D. Articles by Smith, B. D. Search for Related Content PubMed PubMed Citation Articles by Wilson, L. D. Articles by Smith, B. D. Related Articles Related Article Social Bookmarking                            What's this?