Risk for Second Primary Melanoma Increases After Primary Melanoma Diagnosis as Men Age

Older men have an increased risk for second primary invasive melanoma (SPIM) following an initial primary melanoma diagnosis and could benefit from more surveillance in the years following their first diagnosis, according to a study published in JAMA Dermatology.

After being diagnosed with a primary melanoma, patients are more vulnerable to subsequent melanomas. These risks vary, the authors of the present study note, across previous investigations reporting on the likelihood of developing SPIM. These differences represent a pressing issue to address for patients with melanoma because clinical risk assessments can inform approaches to patient follow-ups—which are crucial for early detection and treatment initiation in this population. Regular follow-up can serve a great benefit in this regard; however, if follow-up is prolonged, these instances can give added anxiety to patients, resulting in overtreatment, overdiagnosis, increased burden on clinicians, and higher related costs.

Skin Examination | image credit: magaflopp - stock.adobe.com

To the authors’ knowledge, there have been no reports regarding the timing or risk of SPIM developing on the body site of the initial diagnoses compared with a different site on the body. Considering this lack of information, the researchers conducted a study to investigate the timing and incidence rates between patients’ initial and second primary melanoma diagnosis, as well as evaluate the chances of their melanoma occurring on the same body site as the first diagnosis vs those occurring at different sites.

Data were gathered from the Cancer Registry of Norway from 2008 to 2020 In total, 19,196 individuals were included who had a diagnosis of first primary melanoma during the study period. The mean age of these patients was 62 years. Four percent of patients (n = 766) developed SPIM throughout 98,000 person-years of follow-up. SPIM was diagnosed at an average age of 67 years.

In the first year after a patient’s initial diagnosis, it was assessed that 16.5 (95% CI, 14.8-18.5) of 1000 patients would go on to develop SPIM. The likelihood of this diagnosis within 5 years of their initial diagnosis was 8.1 (95% CI, 7.5-8.8) of 1000 patients and 6.4 (95% CI, 5.9-6.9) per 1000 patients within 10 years.

Throughout the first year of follow-up, SPIM occurred at a rate of 16.8 (95% CI, 14.9-18.7) per 1000 person-years , which dropped to 7.3 (95% CI, 6.0-8.6) per 1000 person-years during the second year of follow-up. For every 1000 person-years in the first year of follow-up, the researchers noted that incidences were higher in male vs female patients (20.3; 95% CI, 17.4-23.3 vs 13.5; 95% CI, 11.1-15.8).

An increased risk of SPIM was associated with the male sex (adjusted rate ratoio (aRR), 1.37; 95% CI, 1.18-1.59) and older age, with men aged 80 years enduring incidence rates over 7 times more compared with those aged 40 years (aRR, 7.33; 95% CI, 3.46-15.51).

There was a median period of 17 (95% CI, 15-20) months between patients’ first and second diagnosis of primary melanoma. Male patients experienced a median interval of 17 months and female patients, 20 months. The authors found these periods decreased with age, as those aged 50 to 59 had an interval of 18 months (95% CI, 13-24); those aged 70 to 79 years, 14 months (95% CI, 7-18); and those 80 years or older, 11 months (95% CI, 7-18).

SPIM developed on the same side as a patient’s initial primary melanoma in 22% of cases, on the opposite side in 25%, and on a different site altogether in 53%.

These findings could change follow-up recommendations for affected patients in Norway, the authors suggest. Current Norwegian guidelines do not consider patient risks for SPIM; however, the authors’ results indicate that increased surveillance could be beneficial in older male patients no matter the characteristics of their initial melanoma.

Reference

Ghiasvand R, Green AC, Veierød MB, Robsahm TE. Incidence and factors associated with second primary invasive melanoma in norway. JAMA Dermatol. Published online February 28, 2024. doi:10.1001/jamadermatol.2023.6251