Weight loss is a very common feature of most cancers. The weight loss is not seen in the initial stages but usually when the cancer is advanced. The weight loss is often significant. The thing to note is that with cancer, the weight loss is not intentional. The individual has no appetite even though he or she has not eaten at all. The bone and muscle mass start to disappear and it is not uncommon to lose 10-15 pounds within a few months. Weight loss is most common with cancers of the lung, colon, bone, pancreas, and breast.