12 Possible Early Warning Signs of Cancer You Should Know

Cancer can develop without causing obvious symptoms in its early stages. When symptoms do appear, they can vary widely depending on the type of cancer, where it develops, and how it affects the body.

Knowing the possible warning signs can help you recognize changes that deserve medical attention. However, it is equally important to remember that having one of these symptoms does not mean you have cancer. Many of these changes are much more commonly caused by infections, inflammation, medications, digestive problems, hormonal changes, or other non-cancerous conditions.

The key is to pay attention to symptoms that are new, unexplained, persistent, or getting worse.

Here are 12 possible early warning signs of cancer you should know.

1. Unexplained Weight Loss

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

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

Cancer is not the only possible explanation. Weight loss can also occur because of thyroid problems, digestive disorders, infections, stress, medication effects, or changes in appetite.

If you continue losing weight without knowing why, speak with a healthcare professional.

2. Persistent or Extreme Fatigue

Feeling tired after a busy day or a poor night’s sleep is normal. But fatigue that is unusually severe or continues despite adequate rest may deserve attention.

Cancer can contribute to fatigue in several ways, including through anemia and changes in the body’s energy use.

Persistent fatigue can also result from many other conditions, including anemia unrelated to cancer, sleep disorders, depression, infections, and nutritional deficiencies.

The important point is not to assume the cause. If unexplained fatigue continues, get it evaluated.

3. A New Lump or Swelling

A new lump, thickening, or swelling anywhere on the body can have many possible causes.

You may notice a lump in the:

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

Some cancers can cause a mass or enlarged lymph node. However, many lumps are caused by infections, cysts, inflammation, or benign growths.

Do not try to diagnose a lump based solely on how it feels. A healthcare professional can determine whether it needs further testing.

4. Unexplained Bleeding or Bruising

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

Potential examples include:

• Blood in the stool
• Blood in the urine
• Coughing up blood
• Unusual vaginal bleeding
• Frequent unexplained nosebleeds
• Bruising without an obvious injury

Certain cancers can cause bleeding or affect blood cells and clotting. However, medications, infections, hemorrhoids, ulcers, hormonal changes, and other conditions can also cause these symptoms.

If bleeding is unexplained or repeatedly occurs, arrange a medical evaluation.

5. Persistent Changes in Bowel Habits

A noticeable change in your usual bowel habits can sometimes be a warning sign.

Watch for persistent:

• Constipation
• Diarrhea
• Alternating constipation and diarrhea
• Changes in stool appearance
• Blood in the stool
• A feeling that the bowel has not completely emptied

These symptoms have many possible causes, including dietary changes, medications, infections, irritable bowel syndrome, and inflammatory bowel conditions. They can also occur with colorectal cancer.

A new bowel change that does not settle should be discussed with a healthcare professional.

6. Persistent Cough or Hoarseness

Most coughs are caused by relatively common conditions such as respiratory infections, allergies, asthma, or irritation.

But a cough or hoarseness that does not go away deserves attention.

Certain cancers, particularly those affecting the lungs, throat, or nearby structures, can cause persistent coughing or voice changes.

Seek medical advice if a cough continues, becomes worse, or is accompanied by symptoms such as coughing up blood, unexplained weight loss, chest discomfort, or difficulty breathing.

7. Changes in the Skin

Your skin can sometimes provide clues that something needs to be checked.

Possible warning signs include:

• A new mole
• A mole that changes in size, shape, or color
• A new or enlarging skin growth
• A sore that does not heal
• A growth that repeatedly bleeds or crusts
• A persistent unusual skin lesion

Skin cancers can appear in different forms and do not always look like the classic image of a dark mole. Some can resemble ordinary skin growths or sores.

If you notice a new or changing skin lesion, consider having it examined rather than attempting to treat it yourself.

8. Persistent Digestive Problems or Trouble Swallowing

Ongoing indigestion, heartburn, abdominal discomfort, nausea, or difficulty swallowing can have many explanations.

However, persistent digestive symptoms can sometimes occur with cancers affecting the digestive system. The National Cancer Institute lists ongoing indigestion or heartburn, abdominal pain, nausea or vomiting, appetite changes, and trouble swallowing among possible cancer symptoms.

You should particularly pay attention when symptoms are new, persistent, progressively worsening, or accompanied by unexplained weight loss or bleeding.

9. Changes in Urination

Changes in your normal urinary habits can have several causes.

Possible warning signs include:

• Blood in the urine
• Pain or burning when urinating
• Difficulty urinating
• Needing to urinate more or less frequently
• A persistent change in normal bladder function

Urinary tract infections, kidney stones, prostate problems, medications, and other conditions can cause these symptoms. Some urinary tract cancers can also cause them.

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

10. Persistent Pain Without a Clear Cause

Pain is common and is usually caused by something other than cancer.

Still, unexplained pain that persists, becomes worse, or repeatedly returns deserves attention.

Cancer can cause pain when a tumor presses against surrounding tissues, organs, blood vessels, or nerves.

The location of the pain may provide clues, but pain alone cannot determine whether cancer is present.

If you have new, persistent pain without an obvious explanation, talk with a healthcare professional.

11. Persistent Fever or Night Sweats

Fever is most often associated with infections, while night sweats can have many causes.

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

These symptoms may be more concerning when they occur together with unexplained weight loss, fatigue, swollen lymph nodes, or other persistent changes.

Rather than assuming the worst, seek medical advice to determine the underlying cause.

12. Persistent Mouth Changes

Changes in the mouth can sometimes be overlooked, especially when they are painless.

Possible warning signs include:

• A sore that does not heal
• A white or red patch
• Persistent mouth pain
• Unexplained bleeding
• Numbness of the lip or mouth
• A lump or thickened area
• Difficulty chewing or swallowing
• Persistent throat discomfort

These symptoms can occur with several conditions, but some are associated with cancers of the mouth and throat.

A sore or unusual mouth change that does not resolve should be examined by a healthcare professional or dentist.

Other Possible Warning Signs

Cancer can produce many different symptoms depending on where it develops. Other possible changes include headaches, vision or hearing problems, neurological symptoms, appetite changes, and jaundice or yellowing of the skin and eyes.

This is why it is important not to focus on a single “cancer symptom.” The overall pattern, duration, and progression of symptoms matter.

When Should You See a Doctor?

You do not need to panic every time you experience a headache, cough, stomachache, or tired day.

In fact, the majority of symptoms that can occur with cancer are more commonly caused by other conditions.

However, make an appointment with a healthcare professional if a symptom:

• Is new and unexplained
• Lasts for several weeks
• Keeps returning
• Gradually becomes worse
• Is accompanied by unexplained weight loss
• Causes unusual bleeding
• Produces a new lump or swelling
• Interferes with normal daily activities

The National Cancer Institute advises people to see a doctor when symptoms persist for a couple of weeks rather than simply waiting indefinitely for them to disappear.

Don’t Wait for Pain

One common misconception is that cancer must become painful before it needs medical attention.

That is not true.

Some cancers may cause few symptoms or no pain during their early stages. This is one reason persistent changes such as a new lump, unusual bleeding, skin changes, or unexplained weight loss should be evaluated even when they are not painful.

Can Cancer Be Found Before Symptoms Appear?

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

Screening is different from diagnostic testing. Screening is generally performed in people who do not have symptoms and is recommended for certain cancers and groups based on factors such as age and individual risk.

Depending on your circumstances, recommended screening may include tests for cancers such as breast, cervical, colorectal, lung, or prostate cancer.

Regular screening does not mean you can ignore new symptoms. If you develop a concerning change, contact a healthcare professional even if your previous screening results were normal.

What Happens If You Have a Concerning Symptom?

A doctor will generally begin by asking about your symptoms, how long they have been present, and whether they are changing.

Depending on the situation, evaluation may include:

• A physical examination
• Blood or urine tests
• Imaging
• Endoscopy or other diagnostic procedures
• A biopsy when appropriate

Having a symptom that can occur with cancer does not mean you have cancer. The purpose of an evaluation is to determine what is actually causing the problem.

Only appropriate medical testing can establish a diagnosis.

Frequently Asked Questions

What is the earliest warning sign of cancer?

There is no single early warning sign that applies to every type of cancer. Possible signs include unexplained weight loss, persistent fatigue, a new lump, unusual bleeding, persistent cough, changes in bowel or bladder habits, skin changes, and other unexplained changes.

Can cancer have no symptoms?

Yes. Some cancers cause few or no noticeable symptoms, particularly in their early stages. This is one reason recommended screening can be important for certain cancers.

Does unexplained weight loss always mean cancer?

No. Unintentional weight loss has many possible causes, including digestive disorders, thyroid problems, infections, stress, medication effects, and other medical conditions. However, significant unexplained weight loss should be evaluated.

Is fatigue a sign of cancer?

Persistent or severe fatigue can occur with cancer, but it is also extremely common with many other conditions. If fatigue is unusual for you, lasts despite rest, or occurs with other unexplained symptoms, discuss it with a healthcare professional.

Can a lump be harmless?

Yes. Many lumps are caused by benign growths, cysts, infections, or inflammation rather than cancer. Nevertheless, a new or unexplained lump should be assessed if it persists or changes.

Can cancer be detected through a blood test?

Some blood tests can provide useful information, but there is no single blood test that can reliably detect all cancers. Tumor-marker tests generally are not effective enough to screen people without symptoms on their own.

Final Thoughts

Knowing the possible warning signs of cancer can help you pay attention to changes in your body without becoming unnecessarily alarmed.

The 12 signs discussed here include unexplained weight loss, persistent fatigue, new lumps, unusual bleeding or bruising, bowel changes, persistent cough or hoarseness, skin changes, ongoing digestive problems, urinary changes, unexplained pain, persistent fever or night sweats, and unusual mouth changes.

Remember that these symptoms are not proof of cancer. Many have much more common and treatable explanations.

The most important thing is to avoid ignoring symptoms that are new, persistent, unexplained, or getting worse. Getting checked can provide reassurance when the cause is harmless and can help ensure that a serious condition is investigated as early as possible.