Cancer Warning Signs: Symptoms That Should Never Be Ignored

The rule of persistence

Almost every symptom on this list has a common, harmless explanation most of the time. What distinguishes a symptom worth investigating is not how severe it is but how long it lasts and whether it is progressing.

A useful rule: anything unexplained that has persisted for three weeks and is not improving deserves a medical opinion. That threshold catches most cancers at a treatable stage without generating unnecessary alarm.

Symptoms warranting assessment

• Unexplained weight loss of more than 5 kg without dieting
• A lump anywhere — breast, neck, armpit, groin, testicle or abdomen — particularly if painless and hard
• Change in bowel habit lasting more than three weeks, or blood in the stool
• Blood in the urine, even once and even without pain
• A cough lasting more than three weeks, or coughing blood
• Difficulty swallowing that is progressing
• A sore or ulcer that has not healed in three weeks
• Any bleeding after menopause, between periods or after intercourse
• A mole changing in size, shape, colour, or that bleeds or itches
• Persistent hoarseness for more than three weeks
• Persistent indigestion or abdominal discomfort in someone over 45
• Unexplained persistent fatigue, night sweats or fever
• Persistent bloating in women, particularly with early fullness on eating

Screening for people without symptoms

• Cervical: Pap smear every three years from 21, or HPV testing every five years from 30
• Breast: clinical examination from 25, mammography from 40
• Oral: monthly self-examination and annual dental review, essential for tobacco users
• Colorectal: screening from 45, earlier with a family history
• Prostate: discuss PSA testing with your doctor from 50, or 45 with a family history
• Lung: discuss low-dose CT screening if you are a long-term heavy smoker

Reducing risk

A substantial share of cancers are preventable. Avoiding all forms of tobacco is the single largest factor. Beyond that: limit alcohol, maintain a healthy weight, stay physically active, eat a diet with plenty of vegetables, fruit and whole grains and less processed and red meat, protect against sun exposure, and take the HPV and hepatitis B vaccines.

Treating chronic infections matters too — hepatitis B and C cause liver cancer, and Helicobacter pylori causes stomach cancer. Both are testable and treatable.

If a biopsy is advised

Biopsy does not spread cancer. This belief is widespread and causes real harm through delayed diagnosis. Without tissue diagnosis, correct treatment cannot be planned, and treating without one risks both undertreating a cancer and subjecting someone to cancer treatment for a benign condition.

Take a second opinion if you wish — that is entirely reasonable and no good doctor objects. But take it quickly rather than spending months deciding.