Which of the following is NOT a warning sign of cancer?

Frequent headaches are not commonly recognized as a direct warning sign of cancer. While headaches can occur in some cancer patients, they are often associated with a variety of benign conditions, such as tension, migraine, or stress-related issues. The presence of headaches alone is generally insufficient to indicate cancer without other accompanying symptoms or risk factors.

In contrast, the other options listed are notable warning signs of cancer. A thickening or lump in the breast can indicate breast cancer, particularly when changes are observed in breast tissue. Indigestion or difficulty swallowing may suggest gastrointestinal tract issues, potentially pointing to cancers such as esophageal or stomach cancer. A sore that does not heal, especially if it persists for weeks, may indicate skin cancer or another malignancy. Therefore, understanding the definitions and implications of these symptoms helps in recognizing potential cancer warning signs effectively.