Relative risk of second malignant neoplasms highest among young adult cancer patients - a population-based registry study in Finland.

BACKGROUND AND PURPOSE: The objective of this study was to explore the incidence of second malignant neoplasms (SMNs) among adult cancer patients in Finland diagnosed with their first primary cancer (FPC) in 1992-2021. MATERIAL AND METHODS: The study used data from the population-based Finnish Cancer Registry (FCR). Risk estimates were calculated using the standardised incidence ratio (SIR), the ratio of observed second cancers compared to the expected numbers assuming the same cancer incidence as the corresponding sex-age-calendar year -split of the general population. RESULTS: A total of 573,379 FPCs were diagnosed during 1992-2021. During the follow-up, 60,464 SMNs were diagnosed. Male cancer patients had neither a decreased nor an increased risk (SIR 1.00 [95% CI, 0.99-1.01]) and female patients had an 8% increased risk (SIR 1.08 [95% CI, 1.06-1.09]) of developing any SMN compared to a FPC in the general population. The highest SIR of any SMN was observed in patients aged 20-39 -years at FPC diagnosis, and the SIR decreased by increasing age at diagnosis. Patients with lymphoid and haematopoietic tissue neoplasms, cancers of the mouth and pharynx, endocrine glands, respiratory and intrathoracic organs, skin, and urinary organs had the highest SIRs, while patients with cancers of the male genital organs and the female breast had the lowest SIRs. INTERPRETATION: Elevated SIRs were observed in cancer patients diagnosed at an early age and for FPCs known to be in large part attributable to lifestyle factors, which highlights the importance of monitoring and encouraging lifestyle changes.

Subsequent malignant neoplasms after primary hematological malignancy in adult patients.

Patients with primary hematological malignancy (HM) are at an elevated risk of subsequent malignant neoplasms (SMNs), which is a common concern after treatment of primary cancer. We identified 45,533 patients aged ≥20 years and diagnosed with primary HM in Finland from 1992 to 2019 from the Finnish Cancer Registry and estimated standardized incidence ratios (SIR) and excess absolute risks per 1000 person-years (EAR) for SMNs. A total of 6076 SMNs were found (4604 solid and 1472 hematological SMNs). The SIRs were higher for hematological SMNs (SIR 4.9, 95% confidence interval [CI] 4.7-5.2) compared to solid SMNs (SIR 1.5, 95% CI 1.4-1.5). The SIRs for hematological SMNs were highest in the young HM patients aged 20-39 years (SIR 9.2, 95% CI 6.8-12.2 in males and SIR 10.5, 95% CI 7.2-14.7 in females) and decreased by age of first primary HM. However, EARs for hematological SMNs were highest in the older patients, aged 60-79 years at their first primary HM (EAR 5.7/1000 and 4.7/1000 in male and female patients, respectively). In conclusion, the incidence of both hematological and solid SMNs were increased in hematological cancer patients. The relative risk (SIR) was highest among younger HM patients with hematological SMNs. The absolute second cancer burden reflected by high EAR arises from solid malignancies in older patients. Our results accentuate the need for vigilance in the surveillance of HM patients.