Potential skin changes to keep an eye on are: moles with uneven borders, or change in color and size (probable signs of melanoma), constant sores that do not heal (may imply skin cancer), yellowing of the skin and eyes (jaundice) (related to liver or pancreatic cancer), dark spots or excessive itching (may indicate cancer of internal organs)
4. Persistent pain

Chronic pain that won’t go away even after you take medications and the amount of rest needed.
Pain that persists and doesn’t seem to have an obvious cause can be an indicator of several diseases, including cancer.
For instance, pain in a bone that becomes persistent and more severe may be due to bone cancer or cancer that has spread to the bones, while severe headaches that don’t resolve with standard treatments may be due to brain tumors. Abdominal or pelvic pain may be an indicator of cancers such as ovarian or colon cancer, while pain in the chest that persists, especially if accompanied by other symptoms, may be an indicator of lung cancer.
In general, persistent or worsening pain that doesn’t seem to have an explanation, especially if accompanied by other symptoms such as weight loss or fatigue, should be evaluated by a doctor and not simply ignored.
5. Unusual lumps or swelling

It is not uncommon to develop lumps and growths on the skin, and in most cases, these are benign conditions such as cysts, lipomas, or swollen lymph nodes. However, it is always a good idea to monitor the situation.
If a lump begins to grow in size, becomes inflamed or painful, persists for more than two weeks, becomes hard to the touch, doesn’t move when pressed against the skin, or develops in areas such as the breasts or the testicles, it is for the best to consult with your doctor.
While these symptoms don’t necessarily indicate a serious problem, they can sometimes be a sign of an infection and other diseases, including cancer.
In the case of unusual changes in the body, including the skin, it is always better to err in the side of caution and seek the advice of a professional rather than hoping the problem would resolve by itself.
6. Changes in Bowel or Bladder Habits

Changes in your bowel or bladder habits can sometimes indicate that something serious is happening in your body, and medical literature lists such changes as symptoms that should not be ignored.