evidence: The researchers, from the American Cancer Society (ACS) and the World Health Organization's (WHO's) International Agency for Research on Cancer, surveyed data from 50 countries to understand the trend. In 14 of these countries, the rising trend was only seen in younger adults, with older adult rates remaining stable. The results are the latest in a host of studies detailing a similar rise of a range of different cancers in the young. [...] While oncologists have typically thought of cancers in younger people as being primarily a consequence of heritable risk factors, such as the BRCA1 and BRCA2 gene mutations in the case of breast cancer, more and more patients have no obvious genetic predisposition. O'Reilly says that in the majority of the young-onset cases she sees, there is no obvious genetic explanation, and when studied in the lab, the tumours carried by patients in their 20s, 30s or 40s appear to be more aggressive compared with a typical pancreatic cancer patient in their 70s.