Learn about 16 symptoms that can sometimes occur with cancer, why they may have many other causes, and which persistent or unusual changes should be discussed with a healthcare professional.
Cancer doesn’t always cause obvious symptoms in its early stages. When symptoms do occur, they can be subtle and easily mistaken for everyday health problems. Importantly, none of these signs by itself means you have cancer. Many are much more commonly caused by infections, medications, hormonal changes, or other non-cancerous conditions.
Still, persistent or unexplained changes deserve attention.
1. Unexplained Weight Loss
Losing a significant amount of weight without intentionally changing your diet or activity can sometimes occur with cancer.
However, thyroid problems, digestive disorders, stress, infections, and other conditions can also cause unexpected weight loss.
2. Unusual or Persistent Fatigue
Cancer-related fatigue can feel different from ordinary tiredness and may not improve adequately with sleep or rest.
Persistent fatigue can also result from anemia, poor sleep, depression, nutritional deficiencies, infections, or chronic medical conditions.
3. An Unexplained Lump or Swelling
A new lump under the skin, in the breast, neck, armpit, or another area should be evaluated if it doesn’t go away.
Most lumps are not cancerous, but their persistence, growth, or other characteristics can determine whether further testing is needed.
4. Unusual Bleeding
Blood in the stool, urine, vomit, or coughing up blood can have many causes, but unexplained bleeding should be medically evaluated.
For women, bleeding after menopause is particularly important to have checked.
5. Changes in Bowel Habits
Persistent changes such as ongoing diarrhea, constipation, narrower stools, or a change in how often you have bowel movements can sometimes be associated with digestive conditions, including colorectal cancer.
6. Persistent Changes in Urination
Blood in the urine, persistent difficulty urinating, unusual urinary frequency, or other significant changes should be discussed with a healthcare professional.
These symptoms can also occur with urinary infections, kidney stones, prostate problems, and other conditions.
7. A Persistent Cough or Hoarseness
A cough that doesn’t go away, recurring coughing up blood, or unexplained persistent hoarseness can warrant evaluation.
Smoking and respiratory infections are common causes, but persistent symptoms shouldn’t simply be ignored.
8. Difficulty Swallowing
Persistent difficulty swallowing food or liquids can have several causes, including reflux and other disorders of the throat or esophagus.
If it continues or progressively worsens, medical assessment is important.
9. Persistent Indigestion or Abdominal Discomfort
Ongoing indigestion, bloating, abdominal pain, or a feeling of fullness may have many benign explanations.
However, persistent or progressively worsening digestive symptoms deserve evaluation, particularly when combined with weight loss or bleeding.
10. Changes in a Mole or Skin Lesion
Watch for changes in a mole’s:
- Size
- Shape
- Color
- Border
- Appearance
A lesion that changes, repeatedly bleeds, crusts, or doesn’t heal should be examined by a healthcare professional.
11. A Sore That Doesn’t Heal
A persistent sore on the skin or inside the mouth that doesn’t heal normally should be checked.
This is particularly important for people who smoke or use tobacco.
12. Persistent Night Sweats or Fever
Unexplained fever or drenching night sweats can occur with some cancers, but infections are much more common explanations.
If these symptoms persist without an obvious cause, seek medical advice.
13. Persistent Pain Without an Obvious Explanation
Ongoing or unexplained pain can sometimes be associated with cancer, depending on its location and other symptoms.
Most persistent pain has other causes, but pain that is new, progressively worsening, or accompanied by other warning signs should be evaluated.
14. Persistent Itching
Unexplained widespread itching can occasionally occur with certain cancers, particularly blood-related cancers.
Much more commonly, however, itching results from dry skin, allergies, medications, eczema, or other skin conditions.
15. Recurrent or Unexplained Infections
Certain cancers and cancer treatments can affect immune function. Repeated unusual infections may therefore warrant medical investigation.
There are many other possible explanations, including medications and immune disorders.
16. Persistent Swelling or Abdominal Enlargement
Unexplained swelling of the abdomen or persistent swelling elsewhere in the body can have numerous causes.
If abdominal enlargement is new and persistent—particularly alongside pain, digestive changes, or unexplained weight loss—it should be assessed.
When Should You Be Concerned?
The key word is persistent.
A single headache, cough, stomachache, or episode of fatigue rarely points to cancer. What deserves attention is a symptom that doesn’t improve, repeatedly returns, progressively worsens, or occurs together with other unexplained changes.
Don’t wait for symptoms to become severe before seeking medical advice.
Screening Matters Too
Some cancers can develop without noticeable symptoms, which is why recommended screening is important. Depending on your age, sex, family history, and risk factors, screening may include tests for colorectal, cervical, breast, or lung cancer.
The Bottom Line
These 16 symptoms are warning signs to discuss with a healthcare professional—not proof that cancer is growing in your body.
Most people with these symptoms will not have cancer. But if something is new, unexplained, persistent, or getting worse, getting it checked can provide reassurance or allow an underlying condition to be treated sooner.