1. Black Stool - Gastric Cancer: Black, tarry stools indicate gastric cancer. Tumors invading blood vessels cause abnormal bleeding in the digestive tract, resulting in darkened stools.

Other symptoms include indigestion, upper abdominal pain, weight loss, anemia, and abdominal masses. High-risk individuals should undergo regular gastroscopy and tumor marker tests.

2. Darkened Complexion - Liver Cancer: Liver cancer can cause a darkening of the face, especially around the eyes.

It disrupts normal pigment metabolism, leading to excess melanin in the blood and a darker complexion. Individuals with a history of alcohol abuse, liver disease, or hepatitis B should undergo regular liver cancer screening.

3. Skin Moles - Melanoma: Melanoma can develop from existing skin moles. Excessive UV exposure, genetics, and skin type are factors.

Melanomas can appear anywhere, with higher incidence in sun-exposed areas. Chronic sun damage is linked to 70% of melanomas.