9 Overlooked Cancer Signs You Shouldn't Ignore

Subtle changes could signal something serious, like breast, colon or lung cancer.

Medically reviewed in July 2022

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An estimated 1,735,350 new cancer cases will be diagnosed in the US in 2018, and more than 600,000 will prove fatal. Cancer can cause a variety of symptoms depending on where it’s located, how much it’s spread and the proximity to organs and tissue.

Symptoms may not be so obvious. Some can be dangerously deceptive even. Seemingly minor changes, like a nagging cough or persistent backache, can sometimes signal cancer. Too often, these aren’t taken seriously until the disease has progressed.

So, how can you distinguish between an innocent ache and a pain you should report to your doctor? “I tell patients that if there are symptoms that are out of the ordinary or persistent or frequent in nature or extreme in intensity, they should seek attention from their primary provider," says oncologist Elwyn Cabebe, MD, of Good Samaritan Hospital in San Jose, California.

Signs and symptoms vary widely, so don't hesitate to talk to your healthcare provider about anything that seems out of the ordinary—especially if you notice one of these nine cancer indicators.

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Unintended weight loss

Unexplained weight loss—10 pounds or more—can be the first sign of cancer, especially with esophageal, lung or stomach cancers, according to the American Cancer Society (ACS). Weight loss affects about 80 percent of people with esophageal and stomach cancers and nearly 60 percent of patients diagnosed with lung cancer, according to the Cancer Treatment Centers of America.

Cancer can deprive your normal cells of the nutrients they need, regardless of what you're eating, which may (in part) explain why the disease can cause a drop in weight. A poor appetite can also decrease your desire to eat; this is particularly common during cancer treatment. Still, unexplained weight loss could be a sign of conditions other than cancer. If you're not actively trying to slim down but still dropping more than a few pounds, make an appointment with your healthcare provider.

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Change in bladder or bowel function

Acute or short-term diarrhea is a common problem, and is typically the result of a virus, bacteria or food sensitivity. Most bouts will last a day or two before going away on their own. Likewise, constipation, characterized by hard, dry stool and fewer than three bowel movements in a week's time, is not often serious and can typically be remedied with water, exercise and fiber.

If these bowel changes—and others like narrowing of the stool—are long-lasting and don't go away on their own, they should be checked by your doctor. Bloody stool is another red flag you should report to your physician. It's not always as obvious as you might think; stool may appear dark red or blackish in color.

These symptoms may indicate an inflamed bowel, like Crohn's disease or ulcerative colitis, but they can also be signs of colon cancer.

Be aware of bladder changes, too, like pain when urinating, bloody urine, more frequent urination or a weak stream. While these signs and symptoms are often caused by a urinary tract infection or an enlarged prostate, they may also indicate urinary tract or prostate cancer. Be sure your physician clears you for cancer after treatment for other problems.

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A fever is often the body's natural response to an infection or illness. Viral and bacterial infections, like the flu or strep throat, as well as some medications and autoimmune diseases, can cause a spike in body temperature.

Fevers rarely point to cancer, but they're common among cancer patients, especially if the disease impacts the immune system. Leukemia and lymphoma are two types of cancer that often result in a fever, but doctors don’t know exactly why these and other cancers cause a rise in temperature. One theory: Cancer cells trigger the immune system to react in this way. Your body might also be struggling to fight infection.

Fevers may come and go over several days or weeks and can also cause night sweats. If you have recurrent fevers or frequent infections accompanied by fatigue and weight loss, see your doctor. These may be signs of serious illness.

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Persistent cough or hoarseness

During cold and flu season, a persistent cough may seem normal, but if you don’t have any of the usual symptoms, like sneezing, stuffy nose or fever, get it checked out. If you've tried to remedy the cough or hoarseness, but nothing seems to work, don't delay a visit to your doctor. A nagging hack could be a sign of lung cancer, the leading cause of cancer deaths in the US. A cough that produces blood is another lung cancer red flag.

Hoarseness, characterized by breathy, raspy or strained sounds when talking, could signal cancer of the thyroid or larynx (voice box). Voice changes that don't improve within two weeks, or are accompanied by difficulty swallowing or pain in the neck or throat, should be evaluated by your doctor.

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Unexplained aches and pains

Pain is usually your body's way of signaling a problem, but the cause of the issue isn't always clear. Maybe you overdid it at the gym or strained a back muscle lifting a heavy box. But if the ache doesn't go away after attempting treatment, it might signal something more serious.

Persistent pain should be reported to a healthcare provider, who can determine if you need further evaluation. Chronic pain could indicate:

  • A brain tumor, which may be associated with headaches
  • Colorectal, kidney and ovarian cancers, which may cause lasting back pain
  • Bone cancer, which can result in pain at rest or with activity

Testicular cancer, which is often accompanied by pain and swelling of the testicle.

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Unusual bleeding or bloody discharge

Blood or bloody discharge from anywhere in the body can be alarming, and might signal cancer, infection, inflammation, trauma or a number of other benign causes. Don't ignore it! Notify your physician to get the proper evaluation and treatment.

Call your doctor at the first sight of blood:

  • In stool, which could be a sign of colon or rectal cancer
  • In urine, which can be associated with bladder and kidney cancer
  • From nipples, which could be a possible red flag for breast cancer
  • From coughing, which has been associated with lung cancer

Unusual vaginal bleeding—blood or bloody discharge not related to your normal menstrual cycle—could also be a worrisome sign. Postmenopausal women, especially, should report vaginal bleeding to their gynecologist who can evaluate them for ovarian and cervical cancer and precancerous lesions.

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The causes of cancer-related fatigue can vary. Some cancers release cytokines—proteins thought to cause fatigue. Others syphon your body's energy, weaken muscles and damage the liver, heart, kidneys or lungs. Cancer can also alter hormones, which may increase fatigue risk. Colon and stomach cancers at times cause undetected bleeding, which can lead to anemia and exhaustion.

Cancer-related fatigue can cause:

  • Low energy and weakness
  • Heaviness in arms and legs
  • Confusion
  • Inability to complete everyday activities
  • Sadness, depression or irritability 

If you’re experiencing any of these signs over a prolonged period, talk to your doctor.

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Mouth and skin sores that won’t go away

Sores that appear in the mouth and won't go away can signify oral cancer. Mouth cancers can occur on the lips, tongue, gums and other oral surfaces; bleeding, loose teeth and white or red patches are also signs. These white patches—precancerous lesions—can be caused by a condition known as leukoplakia, which can develop into oral cancer. Pay particular attention to lesions that won't heal, especially if you smoke, chew tobacco or drink alcohol in excess. These habits can increase your oral cancer risk.

It’s also important to get sores and moles checked for skin cancer—the most common form of cancer in the US. Sores that bleed, ooze, won't go away or heal but return could be signs of skin cancer, like squamous cell carcinoma, basal cell carcinoma or melanoma.

If you notice any of these signs, see your doctor, dentist or dermatologist.

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Skin changes and lumps

We know lumps in the chest area may signal breast cancer, but bumps and growths can also appear in the testicles, lymph nodes and other soft tissue. These could be a sign of cancer.

Become familiar with your body and note any changes to your breasts, testicles and skin. Notify your doctor of changes to the color, size or shape of a wart, mole or freckle, which may indicate skin cancer. There are other signs of breast cancer besides lumps, too, such as thick, red skin on the breast, dimpling of skin or changes in size and shape. Discuss these changes with your doctor as soon as you can—don't wait for your next screening appointment.

Cancer can also cause other skin changes, like jaundice, or yellowing of the skin and eyes. The change in pigmentation could be the result of infections, as well as blood or liver diseases. However, it could also be caused by pancreatic cancer or cancer that's spread to the liver.

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Get screened regularly

Cancer symptoms can be easy to overlook. In some cases, the disease will occur with no noticeable signs or ones that develop only in advanced stages. This makes regular cancer screenings crucial.

"I think what's most important is to get all the cancer-appropriate screening tests," says Dr. Cabebe, including colonoscopies, mammograms and pap smears.

  • Breast cancer: Screening guidelines vary, but the ACS recommends annual mammograms for women of average risk between 45 and 54, with the option to start at 40. At 55, a woman can switch to biennial screenings or continue annual exams, and screenings should continue as long as she is in good health and expected to live for the next 10 years or more.

The US Preventive Services Task Force (USPSTF) recommends biennial mammography for women aged 50 to 74, with the option to start screenings at 40. All women are encouraged to speak with their doctor to come up with the best screening timeline for their situation.

  • Cervical cancer: According to the USPSTF, women between the ages of 21 and 65 should have a Pap test (which screens for cervical cancer) performed every 3 years. Women aged 30 to 65 have another option: an HPV test, with or without the Pap test, every 5 years.
  • Colorectal cancer: Men and women should be screened for colon cancer starting at age 50, according to the USPSTF, and 45, per ACS recommendations. Both organizations recommend screenings until age 75, at which point, you should speak with your healthcare provider about future screenings. Speak also with your doctor about getting screened sooner if you have conditions like IBD or a close relative with colorectal cancer.
  • Lung cancer: The USPSTF recommends yearly lung cancer screenings for people between 55 and 80 who have a history of heavy smoking and still smoke or quit within the last 15 years.
  • Prostate cancer: Starting around age 40, men should speak with a healthcare provider about the risk of prostate cancer and the benefits and drawbacks of screenings.

Those at increased risk for specific diseases should speak with their healthcare provider about personalized screening schedules.

Cabebe also recommends kicking the smoking habit, limiting alcohol intake and maintaining a healthy weight—all of which help reduce your cancer risk. Even with the proper precautions, cancer can still affect anyone. If you see or feel something unusual—even if you suspect it might be harmless—visit your doctor for an evaluation.

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