Some signs are more obvious and clearly recognizable, but are often attributed to a temporary imbalance.

Rectal bleeding or blood in the stool: a warning sign for colon cancer.
Swelling in the neck, armpits, or groin: swollen lymph nodes may indicate a lymphatic system dysfunction.
Abnormal bruising or bleeding: sometimes due to a drop in platelets in certain blood cancers.
Persistent bloating: especially in women, this may indicate ovarian cancer.
Unexplained weight loss: often associated with gastrointestinal or liver cancer.
Don't ignore pain.

Pain is a powerful form of body language. However, when it persists without any apparent reason, it deserves special attention.
Back pain or pain in the right flank: possibly a sign of liver cancer or breast cancer metastases. Pelvic pain: a common sign of ovarian cancer or an enlarged spleen in certain leukemias.
Recurring abdominal pain: persistent abdominal pain can be a symptom of colon cancer.
Chronic cough or chest pain: if this pain lasts for more than three weeks, it could indicate lung cancer.