# Excess mortality in young cancer survivors compared with the general population in Italy: a retrospective study from the Italian population-based cohort of adolescents and young adult cancer survivors

## TL;DR

Young cancer survivors in Italy face seven times higher mortality than the general population, with cancer and non-cancer deaths both contributing significantly.

## Contribution

This study quantifies the long-term excess mortality in young cancer survivors compared to the general population in Italy using a large population-based cohort.

## Key findings

- AYA cancer survivors had a 7.0-fold higher all-cause mortality compared to the general population.
- Excess mortality was highest in the first 5–10 years post-diagnosis and decreased over time.
- Non-cancer mortality remained elevated even 30 years after diagnosis, nearly equaling cancer-related deaths.

## Abstract

Adolescents and young adults (AYA) cancer survivors experience increased morbidity and mortality from second cancers, cardiovascular, infectious, kidney, and other chronic diseases. We aim to calculate all-causes cancer and non-cancer excess mortality of young cancer survivors compared to the general population.

The AYA cohort includes cancer patients diagnosed between 1976 and 2013 and alive at 5 years after diagnosis in 30 population-based Cancer Registries and followed up until 31 December 2019. The standardised mortality ratios (SMRs) and absolute excess risks (AERs) per 100,000 for person-years were calculated.

58,387 5-year survivors were followed up for 427,130 person-years; the median follow-up time was 5.7 years beyond the 5th year after diagnosis. During this time, 4,194 (7.2%) had died by the end of 2019, and only 1.6% were lost to follow-up. Compared with the general population, AYA survivors had higher mortality, overall, the SMR for all-cause mortality was 7.0 (95%CI: 6.8-7.2). The excess of mortality was higher in the first period after diagnosis (5–10 years), SMR 12.8 (95%CI 12.3-13.3), then it decreased, reaching an SMR of 2.2 (95%CI 1.6-3.2) after 30 years.

The excess mortality is mostly due to the malignancy of the primary tumour, but an about 2-fold excess of mortality is also appreciable for non-cancer causes. Young adult cancer survivors face a sevenfold increase in all-cause mortality compared to the general population, with a notable rise in both cancer-related and non-cancer deaths. Thirty years post-diagnosis, the excess risk from cancer and non-cancer causes becomes nearly equal.