Which sign may be an early warning sign of cancer?

A sore that does not heal can indeed be an early warning sign of cancer, particularly skin cancers or other types of malignancies. In the early stages of cancer, the body's normal healing processes may fail, leading to the persistence of sores or wounds that do not respond to treatment as expected. This can indicate abnormal cellular activity, which is a hallmark of cancerous changes. Recognizing this warning sign is crucial, as early detection often leads to more effective treatment options and better outcomes for the patient.

In contrast, while a persistent cough can be associated with various conditions, it is not as specific as a non-healing sore regarding a direct link to cancer. Unexplained weight gain is generally less commonly associated with cancer compared to weight loss, which is more frequently noted. Frequent headaches may arise due to numerous causes, including stress or tension, and while they can be associated with serious issues, they are not considered a major red flag for cancer in the same way as a non-healing sore is.