Unexpected weight loss. For many women, the first sign of cancer is unexplained weight loss of 10 pounds or more. Most people with cancer lose weight eventually and this sign isn't characteristic of any particular form of cancer. Unexplained weight loss from cancer can be caused by many factors, including many that aren't well understood. During treatment, it can be the result of depression, nausea, and other side effects of treatment. Even before the cancer is diagnosed, weight loss may occur as cancer cells use up more of the body's energy supply or by releasing substances that interfere with how the body creates energy from food.
