9 Cancer Symptoms You Should Never Ignore

As if there weren't enough reasons to hate cancer, here's one more: Its symptoms can be dangerously deceptive. Even seemingly minor things, like a nagging cough or backache, can sometimes point to cancer—but the signs often aren’t taken seriously until it’s too late. 

So when should you worry? “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 so they can help decide what the issue is,” says oncologist Elwyn Cabebe, MD, of Good Samaritan Hospital. Click through to see nine symptoms to keep an eye on.

According to the American Cancer Society (ACS), one of the first signs of cancer may be an unexplained drop of 10 or more pounds. Some of the weight loss may stem from muscle loss and weakness from the body trying to fight back against the disease. This tends to be most indicative of pancreatic and esophageal cancers.

Diarrhea, constipation, change in size of your stool, narrowing of stool—these are all symptoms to have checked out. Another sign is blood in the stool. While it sounds dramatic, it often isn’t that noticeable. The stool will appear dark red or blackish in color. While these symptoms may indicate other uncomfortable bowel problems, they may also be early signs of colon cancer.

A fever is often the body's natural response to an infection or illness. And while fevers rarely point to cancer, they are quite common in cancer patients—especially if the cancer impacts the immune system. Doctors aren't quite sure why some cancers cause fevers and others don't; one train of thought is that fever is brought on by a tumor's toxins. Fevers may develop daily or you might go weeks without one. They can also come in the form of night sweats. When related to cancer, fever may be an early sign of blood cancer (leukemia and lymphoma).

During cold and flu season, a persistent cough may seem normal, but if you don’t have any other of the usual cold and flu symptoms, you should get it checked out. It may also be of concern if you've tried to remedy the bad cough or sore throat but nothing seems to work. Blood may accompany the cough. A long-lasting cough or hoarseness may be an indicator of lung cancer.

Pain is usually a sign that something's up with your body, and that can mean a number of things. But pain that doesn't go away after attempting to treat it might signal cancer. For example, continuous headaches may stem from a cancerous brain tumor, while consistent back pain may be a sign of colon, rectum or ovarian cancer.

Blood or discharge from anywhere in the body can be alarming, and this symptom can make an appearance in both early and late stages of cancer. The ACS gives examples of what bloody leakage may mean for different areas of the body:

• In the stool: colon or rectal cancer
• In the urine: bladder or kidney cancer
• From the nipples: breast cancer
• From coughing: lung cancer 

According to the ACS, it's not exactly understood what causes the fatigue. But fatigue or extreme exhaustion that doesn't improve with rest is one of the most common cancer symptoms. In colon or stomach cancers, this exhaustion may stem from blood loss that isn't noticeable. Other signs of cancer-related fatigue include feeling too tired to complete everyday activities, trouble concentrating and feeling weak, irritable and upset.

These symptoms most often appear on the skin as a mole or sore that won't heal, or in the mouth, which may signify either skin or oral cancer. It can be a major red flag for people who smoke, chew tobacco or drink alcohol in excess. Other things to watch for are white patches in the mouth and tongue that have been there for a while. These patches may indicate leukoplakia, a precancerous area that can become mouth cancer if not treated. See your doctor or dentist for treatment options if you notice these signs.

Cancer can sometimes be felt through the skin; it’s well known that lumps in the chest area may be breast cancer. The ACS reports that cancerous lumps may also appear in testicles, lymph nodes and within other soft tissues of the body. Some breast cancers may also show up as red or thickened skin instead of a lump. If you notice any changes in color, size or shape of a wart, mole or freckle, see your doctor, as this could be a sign of a skin cancer, such as melanoma. In addition to skin cancers, other cancers can cause changes in the skin. For example, yellow skin or eyes (jaundice) might point to pancreatic cancer.

Some cancers may not cause any symptoms at all, or only when they’re at an advanced stage, which is why cancer screening is so crucial. "I think what's most important is to get all the cancer-appropriate screening tests, and that includes colonoscopies, mammograms, pap smears, etc.," says Dr. Cabebe. In addition to these tests, he recommends making certain lifestyle changes—like cutting out smoking or watching your alcohol intake—to help reduce your risk of cancer. 

See more from Dr. Cabebe