Cancer Incidence and Mortality in the Oldest Old: A Nationwide Study in Finland.

The world's population is aging rapidly. This study reports the burden of cancer in the "oldest old" (aged ≥85 years) in Finland, 1953-2017, and estimates age-specific cancer rates in the older population (65-99 years) for 1988-2017. The Finnish Cancer Registry provided data on all cancer diagnoses, cancer deaths, and other deaths in cancer patients in Finland for 1953-2017. Between 1953-1957 and 2013-2017, the proportion of incident cancers in those aged ≥85 years increased from 1.5% to 9.6% (597 to 15,360 new cases), and in 2013-2017, more new cancers were diagnosed at ages ≥85 years than ages <50 years. Cancer incidence and excess mortality attributable to cancer peaked at ages 85-94 years and declined subsequently, whereas cancer-specific mortality continued to increase or plateaued. Due to demographic changes, the number of new cancers in the oldest old has increased substantially in Finland, and currently nearly 1 in 10 cancers are diagnosed in this age group. The increasing cancer burden in the oldest old poses a major challenge for health care and needs to be addressed in designing clinical research and reporting of cancer registries. In older populations with competing risks of death, we propose excess cancer mortality as a measure of cancer-related mortality.

Familial aggregation of early-onset cancers.

This registry-linkage study evaluates familial aggregation of cancer among relatives of a population-based series of early-onset (≤40 years) cancer patients in Finland. A cohort of 376,762 relatives of early-onset cancer patients diagnosed between 1970 and 2012 in 40,538 families was identified. Familial aggregation of early-onset breast, colorectal, brain and other central nervous system (CNS) cancer and melanoma was explored by standardized incidence ratios (SIR), stratified by relatedness. Gender-, age- and period-specific population cancer incidences were used as reference. Cumulative risks for siblings and offspring of the proband up to age ≤40 years were also estimated. Almost all early-onset cancers were sporadic (98% or more). Among first-degree relatives, SIR was largest in colorectal cancer (14, 95% confidence interval 9.72-18), and lowest in melanoma (1.93, 1.05-3.23). Highest relative-specific SIRs were observed for siblings in families, where also parent had concordant cancer, 90 (43-165) for colorectal cancer and 29 (11-64) for CNS cancer. In spouses, all SIRs were at population level. Cumulative risk of colorectal cancer by age 41 was 0.98% in siblings and 0.10% in population, while in breast cancer the corresponding risks were 2.05% and 0.56%. In conclusion, early-onset cancers are mainly sporadic. Findings support high familial aggregation in early-onset colorectal and CNS cancers. Familial aggregation in multiplex families with CNS cancers was mainly attributed to neurofibromatosis and in colorectal cancer to FAP- and HNPCC-syndromes. The pattern of familial aggregation of early-onset breast cancer could be seen to support very early exposure to environmental factors and/or rare genetic factors.