20 Possible Early Signs of Cancer You Should Know

Cancer does not always cause obvious symptoms in its early stages. In fact, some cancers may produce few or no noticeable warning signs until they have grown or spread. When symptoms do occur, they can vary considerably depending on the type of cancer, where it develops, and how it affects nearby tissues or the rest of the body.

At the same time, having one of these symptoms does not mean you have cancer. Many of the signs discussed below are much more commonly caused by infections, injuries, medications, digestive problems, hormonal changes, or other non-cancerous conditions.

Still, persistent, unexplained, or worsening changes deserve attention. Knowing what to watch for can help you decide when it is appropriate to speak with a healthcare professional.

Here are 20 possible early signs of cancer you should know.

1. Unexplained Weight Loss

Losing weight without intentionally changing your diet or activity level can sometimes be a warning sign of an underlying health problem.

The American Cancer Society lists unexplained weight loss of around 10 pounds or more as a possible cancer symptom.

Cancer is not the only possible explanation. Thyroid problems, digestive disorders, infections, stress, medication effects, and other conditions can also cause unexpected weight loss.

If your weight is falling without an obvious reason, particularly if the change continues, talk with a healthcare professional.

2. Persistent or Unusual Fatigue

Everyone feels tired occasionally, especially after a busy day or a poor night’s sleep.

Cancer-related fatigue can be different. It may be persistent, unusually severe, and not improve adequately with rest. Some cancers can contribute to fatigue through anemia or other changes affecting how the body functions.

Persistent fatigue has many possible causes, including sleep disorders, anemia, depression, infections, and nutritional deficiencies. It should therefore be investigated rather than automatically attributed to cancer.

3. An Unexplained Lump or Swelling

A new lump or swelling anywhere on the body should be taken seriously if it persists or changes.

Possible locations include the:

• Breast
• Neck
• Underarm
• Groin
• Abdomen
• Testicle
• Skin or soft tissue

Some cancers can cause a mass or enlarged lymph node. However, most lumps are not cancerous and may result from infections, cysts, benign growths, or other conditions.

A healthcare professional can determine whether a lump needs further evaluation.

4. Changes in the Skin

Skin changes can sometimes provide an early clue, particularly for skin cancers.

Watch for a:

• New or changing mole
• Spot that changes in size, shape, or color
• Growth that continues to enlarge
• Persistent rough or scaly patch
• Sore that does not heal
• Lesion that repeatedly crusts or bleeds

Not every unusual skin mark is cancer. However, a new or changing skin lesion should be examined by a healthcare professional, particularly if it persists or continues changing.

5. A Sore That Does Not Heal

Most minor cuts and sores gradually heal.

A sore that remains open, repeatedly returns, bleeds, crusts, or fails to heal over several weeks should be checked.

This can be particularly important when the sore occurs on an area of skin that receives substantial sun exposure. Certain skin cancers can appear as sores that do not heal normally.

Persistent sores in the mouth should also be evaluated, particularly when accompanied by pain, bleeding, numbness, or other changes.

6. Unusual Bleeding

Unexpected bleeding can have many causes, but unexplained or persistent bleeding should not be ignored.

Examples include:

• Blood in the stool
• Blood in the urine
• Coughing up blood
• Vomiting blood
• Unusual vaginal bleeding
• Repeated unexplained nosebleeds
• Bleeding that is heavier or different from normal

Some cancers can cause bleeding directly or indirectly.

However, conditions such as hemorrhoids, infections, ulcers, medications, and hormonal changes can also cause bleeding. A healthcare professional can help determine the source.

7. Changes in Bowel Habits

A persistent change in bowel habits can be worth discussing with a doctor.

Possible changes include:

• Ongoing diarrhea
• Persistent constipation
• Alternating diarrhea and constipation
• A noticeable change in stool appearance
• A persistent feeling that the bowel has not completely emptied

These symptoms can occur for many reasons, including diet, medications, irritable bowel syndrome, infections, and inflammatory bowel conditions. They can also occur with colorectal cancer.

The important factor is a new, persistent, or unexplained change.

8. Blood in the Stool

Blood in the stool should be evaluated rather than automatically assumed to be hemorrhoids.

Depending on where bleeding occurs in the digestive tract, blood may appear bright red, dark, or may not be visible at all.

Colorectal cancer is one possible cause, but there are many other explanations for blood in the stool.

If you notice repeated or unexplained blood in your stool, contact a healthcare professional for appropriate evaluation.

9. Persistent Cough

A cough is extremely common and is usually caused by conditions such as respiratory infections, allergies, asthma, or irritation.

However, a cough that does not go away or keeps getting worse deserves medical attention.

Cancer affecting the lungs or nearby structures can sometimes cause persistent coughing. A cough may also occur with hoarseness, chest discomfort, or coughing up blood.

A persistent cough should not automatically be considered cancer, but it should be investigated if it continues without an obvious explanation.

10. Ongoing Hoarseness or Voice Changes

A temporary change in your voice can happen after a cold, allergies, or excessive voice use.

Persistent hoarseness, however, may require evaluation.

Changes in the voice can occur when disease affects structures involved in speech, including the throat or larynx.

If hoarseness continues or repeatedly returns without a clear explanation, speak with a healthcare professional.

11. Difficulty Swallowing

Trouble swallowing, sometimes called dysphagia, can make eating or drinking uncomfortable or difficult.

It may feel as though food is getting stuck, or swallowing may require unusual effort.

There are many possible causes, including acid reflux, neurological disorders, inflammation, and structural problems. Certain cancers of the throat or digestive tract can also cause swallowing difficulties.

Persistent or progressively worsening difficulty swallowing should be evaluated.

12. Persistent Indigestion or Abdominal Discomfort

Occasional indigestion is common.

Persistent indigestion, unexplained abdominal discomfort, ongoing heartburn, or pain after eating can have many causes, including reflux, ulcers, gallbladder problems, and other digestive conditions.

In some cases, persistent digestive symptoms can be associated with cancer. The National Cancer Institute lists ongoing heartburn or indigestion, abdominal pain, nausea, and other eating-related problems among symptoms that can occur with cancer.

If digestive symptoms persist despite reasonable lifestyle changes or treatment, discuss them with a healthcare professional.

13. Persistent Bloating or Abdominal Swelling

Feeling bloated occasionally is common, particularly after certain meals.

Persistent or unusual abdominal swelling can have numerous causes. In some circumstances, abdominal masses or fluid buildup can produce a feeling of fullness or visible swelling.

Persistent bloating accompanied by weight loss, appetite changes, abdominal pain, or other unexplained symptoms deserves medical attention.

14. Changes in Urination

Changes in bladder habits can sometimes be a sign that something needs investigation.

Potential warning signs include:

• Blood in the urine
• Pain or burning when urinating
• Needing to urinate more frequently
• Difficulty urinating
• A noticeable change in normal urinary patterns

These symptoms are often caused by urinary tract infections, kidney stones, prostate problems, medications, or other conditions. They can also occur with certain urinary tract cancers.

Blood in the urine, in particular, should be medically evaluated even if it happens only once.

15. Recurrent Fever or Night Sweats

Fever is commonly caused by infections, and night sweats can occur for many reasons.

However, unexplained fever or significant night sweats that persist or repeatedly occur can sometimes accompany cancer.

These symptoms are particularly important when they occur alongside unexplained weight loss, persistent fatigue, swollen lymph nodes, or other ongoing changes.

16. Persistent Pain Without a Clear Cause

Pain is one of the body’s most common warning signals, but it does not automatically indicate cancer.

Cancer-related pain may occur when a tumor presses against surrounding tissues, organs, nerves, or other structures.

Pay particular attention to pain that:

• Is new and unexplained
• Persists despite usual measures
• Gradually becomes worse
• Repeatedly returns without an obvious cause
• Occurs with other unexplained symptoms

Persistent pain deserves evaluation even when cancer is unlikely because another treatable condition may be responsible.

17. Unexplained Bruising

Occasionally bumping into furniture can produce a bruise that you remember causing.

Repeated bruising without an obvious injury, particularly when it is new or unusually extensive, should be discussed with a healthcare professional.

Some cancers and other medical conditions can affect blood cells or clotting, potentially contributing to unusual bruising or bleeding.

Medications such as blood thinners can also increase bruising, so make sure your healthcare professional knows about all medicines you take.

18. Persistent Mouth Changes

Changes inside the mouth can sometimes warrant attention.

Possible warning signs include:

• A sore that does not heal
• Persistent mouth pain
• Unexplained bleeding
• Numbness
• A white or red patch
• Ongoing difficulty swallowing

The National Cancer Institute lists white or red patches, bleeding, pain, and numbness among possible mouth-related cancer symptoms.

Tobacco and alcohol use can increase the risk of some oral cancers, but anyone with persistent unexplained mouth changes should consider getting them checked.

19. Persistent Headaches or Neurological Changes

Headaches are extremely common and are rarely caused by cancer.

However, a new or persistent headache accompanied by other neurological changes may require medical assessment.

Potential concerning changes can include:

• New vision problems
• Hearing changes
• Seizures
• Facial weakness
• Persistent or unusual headaches
• Other changes in neurological function

The NCI lists headaches, seizures, vision changes, hearing changes, and facial drooping among neurological symptoms that can occur with some cancers.

Sudden severe neurological symptoms should always be treated as a medical emergency rather than assumed to be cancer.

20. Persistent Loss of Appetite

A temporary decrease in appetite can happen during stress, illness, hot weather, or after a large meal.

A prolonged or unexplained loss of appetite can sometimes accompany cancer, particularly when it occurs alongside fatigue, weight loss, nausea, or other persistent symptoms.

If you regularly have little interest in food and cannot identify a reasonable explanation, speak with a healthcare professional.

When Should You See a Doctor?

A single symptom usually does not mean that you have cancer.

Many symptoms associated with cancer are much more commonly caused by other conditions. For example, swollen lymph nodes are often caused by infection, and blood in the stool has many possible explanations besides cancer.

However, it is sensible to seek medical advice when a symptom is:

• New and unexplained
• Persistent for several weeks
• Getting worse
• Repeatedly returning
• Interfering with everyday activities
• Occurring alongside other unusual symptoms

The NCI recommends speaking with a doctor about symptoms that last for a couple of weeks rather than simply waiting for them to disappear.

Do Not Wait for Pain

An important misconception is that cancer must cause pain before it becomes serious.

That is not true. Some cancers may cause little or no pain, particularly during earlier stages.

This is why changes such as an unexplained lump, abnormal bleeding, persistent cough, skin changes, or unexplained weight loss should be evaluated even if they are painless.

Can Cancer Be Found Before Symptoms Appear?

Yes. Some cancers can be detected through screening before symptoms develop.

Screening recommendations depend on factors such as age, sex, personal and family history, and individual risk. Examples of established screening approaches include certain tests for colorectal, breast, cervical, and lung cancers in people who meet specific criteria.

Screening is different from investigating symptoms. If you develop a new or concerning symptom, you should not wait for your next routine screening appointment.

What Happens If You Have a Concerning Symptom?

A healthcare professional may begin by asking when the symptom started, whether it has changed, and what other symptoms you have experienced.

Depending on your situation, evaluation may include a physical examination, blood or urine tests, imaging, or other diagnostic procedures.

A concerning symptom does not equal a cancer diagnosis. The purpose of evaluation is to determine what is causing the change and provide appropriate treatment if needed.

Final Thoughts

Knowing the possible early signs of cancer does not mean living in fear of every ache, cough, or change in your body. Most symptoms discussed in this article have causes other than cancer.

The important lesson is to pay attention to persistent, unexplained, unusual, or worsening changes.

Possible warning signs include unexplained weight loss, persistent fatigue, new lumps, skin changes, non-healing sores, unusual bleeding, bowel or bladder changes, ongoing cough or hoarseness, difficulty swallowing, persistent abdominal symptoms, unexplained pain, unusual bruising, mouth changes, neurological symptoms, and prolonged loss of appetite.

Early evaluation can be valuable because it may identify cancer at a stage when treatment is more likely to be successful—and it can also uncover many non-cancerous conditions that need treatment.

If you notice a new symptom that persists for several weeks, gets worse, or has no clear explanation, make an appointment with a healthcare professional rather than trying to diagnose yourself.

This article is for general educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. If you have severe or rapidly worsening symptoms, seek urgent medical attention.