The increase in breast cancer rates among younger patients is occurring as the incidence of other early-onset cancers — including colorectal, gastric, kidney and liver cancer — is also on the rise, though cancer among patients under 50 is still relatively rare overall, Dr. Partridge said.

Cancer diagnoses are shifting from older to younger adults and from men to women, according to a report released Thursday by the American Cancer Society.

Cancer rates for young women are sharply rising, with women under 50 more likely to develop cancer than their male counterparts — by 82%. The rate of cancer for young women “h