Melanoma staging system inaccurately reflects recurrence, mortality risk

Key takeaways:

• Recurrence was lower in stage IIIA than IIB (29.7% vs. 33.2%) and lower in stage IIIB than IIC (35.9% vs. 36.8%).
• Of patients with recurrence, 56.6% of them also experienced distant recurrence.

Findings from a nationwide, population-based cohort study revealed that the current staging system used for melanoma does not represent accurate recurrence and mortality.

Specifically, patients in the study with stage IIB and IIC melanoma faced a poorer prognosis than patients with stage IIIA and IIIB melanoma, indicating an inaccurate reflection of melanoma substages.

“Knowledge of the stage-specific risk of recurrence and death from melanoma is essential for optimal treatment and surveillance organization,” Neel M. Helvind, MD, PhD, of the department of plastic surgery at Copenhagen University Hospital in Herlev, Denmark, and colleagues wrote. “This knowledge is needed for patient communication, to aid patient selection for adjuvant treatment, and to guide decision-making regarding adjuvant treatment for patients with stage II and IIC melanoma.”

The researchers assembled a population-based cohort study to assess the stage-specific rates of recurrence and death from melanoma and melanoma-specific recurrence-free survival.

The study, conducted in Denmark, included 25,720 Danish patients aged 18 years or older that were diagnosed with first-time stage IA to IV cutaneous melanoma between Jan. 1, 2008, and Dec. 31, 2019.

Results showed that the increasing risk for recurrence and melanoma-specific mortality was not associated with increasing stages as outlined in the American Joint Committee on Cancer 8th Edition Cancer Staging Manual (AJCC8).

A total of 10.6% of patients developed recurrence, with melanoma-specific mortality among these patients comparable between stages. Stages IIIA and IIA presented a melanoma-specific mortality of 13% and 13.6%, respectively, whereas stages IIIB and IIB presented an 18.4% and 22% melanoma-specific mortality.

Of the patients that experienced recurrence, 56.6% also experienced distant recurrence, which was seen alone (39.9%) or with synchronous locoregional recurrence (16.7%). Distant recurrence was present at the time of first recurrence across all substages of melanoma.

“The high proportion of distant recurrences suggests a larger role of hematogenous dissemination in the metastatic pathways than previously assumed,” the authors said.

The study showed that there is a comparable risk for recurrence in stages IIIA and IIB (29.7% vs. 33.2%) and in stages IIIB and IIC (35.9% vs. 36.8%), respectively. According to the authors, this confirms that “the AJCC8 substages do not accurately reflect the risk of recurrence and mortality.”