Multiple Cutaneous (pre)-Malignancies

Abstract

The three most common cutaneous malignancies are derived from melanocytes and keratinocytes (ordered in decreasing aggressiveness): melanoma, squamous cell carcinoma (SCC) and basal cell carcinoma (BCC). This thesis focuses only on these three types of cancer and their precursors. The incidence rates of the three most common skin cancers are rising and show large variations between countries. The majority of skin cancer patients have a relatively good prognosis, which has implications for treatment, follow-up strategies and risks of developing multiple cutaneous (pre)-malignancies. Important topics like follow-up and early detection of skin cancer remain a subject of debate. In this thesis the burden of multiple cutaneous malignancies and their consequences for patients, doctors and health care systems are described. The first part encompasses a large systematic review and meta-analysis and two large population-based cohort studies to investigate risks of developing a melanoma, SCC or BCC after a melanoma or keratinocyte carcinoma (including SCC and BCC). This information could serve as information for health care systems. Further, secondary prevention seems pivotal in this patient group. In the second part time trends of thin melanomas in The Netherlands were analyzed and the prevalence of actinic keratosis (AK), its risk factors and association with skin cancer in an elderly population were investigated (the Rotterdam Study, a Dutch population-based cohort study). In the third part conditional survival of melanoma in The Netherlands was described. It gives a more optimistic message of their future to melanoma survivors than the traditional survival rates and could reduce anxiety concerning their melanoma diagnosis in the past. Also survival of patients with multiple melanoma were compared with patients with single primary melanoma using time-varying co-variates in a Cox proportional Hazard model. This thesis contributes to the current knowledge on the occurrence of multiple cutaneous malignancies and associated mechanisms of field cancerization and overdiagnosis and could therefore be used as material for patient education and follow-up strategies.