A persistent change in bowel movements or urination can sometimes be an important warning sign.

Examples include:

• Blood in the stool or urine
• Persistent constipation or diarrhea
• A major change in stool appearance
• Increased urinary frequency
• Difficulty urinating
• Persistent abdominal discomfort

These symptoms have many noncancerous causes, including hemorrhoids, infections, dietary changes, medications, prostate problems, and gastrointestinal disorders.

Still, unexplained blood in the stool or urine should be medically evaluated, particularly if it persists or recurs.

9. Persistent Changes in the Mouth or Throat

A sore in the mouth that doesn't heal, persistent hoarseness, difficulty swallowing, an unexplained lump, or unusual bleeding can sometimes warrant evaluation.

Most mouth sores are not cancer.

For example, ordinary canker sores commonly disappear within a relatively short period.

But a lesion that doesn't heal as expected, repeatedly returns in the same location, or is accompanied by persistent pain or difficulty swallowing should be checked by a dentist or doctor.

10. The Most Important Warning Sign: A Change That Doesn't Go Away

Perhaps the most useful principle is not to focus on one isolated symptom.

Instead, pay attention to persistent or progressive changes.

A bruise that appears after bumping your leg and gradually disappears is very different from unexplained bruising that repeatedly appears.

A small skin mark that remains unchanged for years is different from a mole that suddenly changes shape and color.

A temporary sore throat is different from persistent hoarseness or swallowing difficulty.

The pattern and duration matter.