Malignant and in situ subtypes of melanoma are associated with basal and squamous cell carcinoma and its precancerous lesions

Background: Patients with cutaneous malignant melanoma (CMM) are at increased risk of non-melanoma skin cancers (NMSCs) and possibly precancerous lesions. Objectives: To analyse the association between CMM and not only NMSCs but also precursor lesions, actinic keratosis (AK) and Bowen disease (BD). Materials & Methods: The Finnish Cancer Registry data was used to calculate the age-standardized incidence ratio during 2000-2013 for basal (BCC) and squamous (SCC) cell carcinoma in patients with CMM. All tissue material collected from 70,420 subjects during 2000-2013 and reposited in the Biobank of Eastern Finland was used to calculate the age-standardized prevalence of BCC, SCC, BD and AK in CMM patients. Results: In both genders, the age-standardized incidence ratio of BCC and SCC was increased in CMM patients. The age-standardized prevalence of NMSCs and precursor lesions was higher in patients with CMM than in those without CMM, and was higher in CMM patients with immunosuppression (IS) than in those without IS. The association of M-Snomed subtypes, lentigo maligna (LM), melanoma in situ (MIS) and malignant melanoma (MM) with AK and/or BD was stronger than with BCC. LM revealed the highest association with the combination of AKBD-SCC. Male subjects showed a higher age-standardized prevalence of CMM, MM and BCC than females, but the opposite was observed for AK. Conclusion: Melanoma increases the risk of NMSCs, and IS may enhance this risk. Both malignant and in situ subtypes of melanoma associate with not only BCC and SCC, but also precancerous lesions.

High regional mortality due to malignant melanoma in Eastern Finland may be explained by the increase in aggressive melanoma types.

BACKGROUND: A regional skin cancer prevention program in Eastern Finland revealed a relatively high age-standardized mortality due to malignant melanoma during 2013-2017. An explanation for this is needed. PURPOSE: To analyse the 543 melanoma samples in 524 subjects collected during 2000-2013 at Kuopio University Hospital and reposited in the Biobank of Eastern Finland. A focus was directed to factors related to metastasis. METHODS: The samples were analysed anonymously by examining the histopathological report, referral text and the list of diagnoses. A possible state of immunosuppression was evaluated. RESULTS: The mean age at the diagnosis of malignant melanoma (MM), lentigo maligna (LM) and melanoma in situ was relatively high, i.e., 66.2, 72.1 and 63.3, respectively. Especially the MM type increased markedly during 2000-2013. In further analyses of a representative cohort of 337 samples, the proportion of nodular melanoma and LM/LMM melanoma was relatively high, 35.6 and 22.0%, respectively, but that from superficial spreading melanoma relatively low (33.8%). Metastasis correlated with immunosuppression, male gender, Clark level, Breslow thickness, ulceration, mitosis count, invasion into vessels and/or perineural area, microsatellites, melanoma subtype, body site, recidivism, and the absence of dysplastic nevus cells. CONCLUSION: The marked increase in aggressive melanomas with associated metastasis, and the relatively high age at diagnosis, can partially explain the mortality.