Unexplained pain
Chronic pain that has no clear cause is another potential warning sign of cancer. Persistent headaches may be associated with brain tumors, while back pain can be a symptom of cancers of the ovaries, kidneys, or spine. Bone pain may indicate that cancer has spread to the bones.

Skin changes

Unusual changes in the skin, such as darkening, yellowing, or redness, may indicate cancer. Skin cancer can appear as a new mole, a change in an existing mole, or a sore that won’t heal. Additionally, jaundice (yellowing of the skin or eyes) may be a sign of liver cancer.

Changes in bowel or bladder habits
Sudden, unexplained changes in bowel or bladder habits may indicate cancer. Constipation, diarrhea, or stool changes that last for more than a few days may be linked to colon or rectal cancer. Similarly, changes in urination, such as frequent urination or blood in the urine, may indicate bladder or prostate cancer.