How Does Cancer Cause Signs and Symptoms?
Cancer symptoms vary depending on location, size, and impact on surrounding tissues and organs. If cancer spreads (metastasizes), symptoms can appear in different parts of the body.
Signs and symptoms are ways the body signals distress, injury, or illness:
- Signs, such as fever or bleeding, can be observed and measured by others.
- Symptoms, such as pain or fatigue, are experienced by the individual.
A cancerous tumor may become or press against nearby organs, blood vessels, lymphatic tissue, or nerves, causing discomfort and functional changes. Additionally, cancer can trigger symptoms like fever, extreme fatigue, or unexplained weight loss by depleting the body’s energy supply or releasing substances that alter metabolic functions. The immune system may also react in ways that contribute to these symptoms.
Cancer Symptoms to Watch For
Not all symptoms indicate cancer, but if you experience any of the following, consider consulting your doctor:
Abnormal Menstrual Cycles or Pelvic Pain
Occasional irregular periods or cramps are standard. However, persistent pain or cycle changes may signal cervical, uterine, or ovarian cancer.
Bowel or Urinary Changes
Significant changes in bowel or bladder function can indicate colon, prostate, or bladder cancer. Warning signs include persistent constipation or diarrhea, black or red blood in stools, tar-like stools, frequent urination, or blood in urine.
Persistent Bloating
Occasional bloating is normal, but bloating lasting more than two weeks may indicate ovarian or gastrointestinal cancers.
Breast Changes
Look for lumps, dimpling, discoloration, nipple changes, or unusual discharge. While breast cancer is more common in women, men can develop it too.
Chronic Cough
A persistent dry cough lasting over two weeks may indicate lung cancer.
Persistent Headaches
Headaches lasting more than two weeks and unresponsive to usual treatments may indicate a brain tumor.
Difficulty Swallowing
If food feels stuck in your throat or swallowing is painful for more than two weeks, it may signal throat, lung, or stomach cancer.
Excessive Bruising
A bruise from bumping into furniture is normal, but frequent, unexplained bruising in unusual locations could indicate blood-related cancers.
Frequent Fevers or Infections
Recurring high fevers or frequent infections may suggest a weakened immune system due to leukemia or lymphoma.
Mouth Changes
Persistent sores, lesions, or painful areas in the mouth—especially in smokers or heavy drinkers—may indicate oral cancer.
Skin Changes
Monitor moles or birthmarks using the ABCDE rule:
- Asymmetry: One half doesn’t match the other.
- Border: Irregular or blurred edges.
- Color: Uneven shades of brown or black.
- Diameter: Larger than a pencil eraser.
- Evolving: Changes in size, shape, or bleeding.
Chronic Pain
Unexplained, persistent pain anywhere in the body that doesn’t respond to treatment should be evaluated.
Persistent Fatigue
Extreme, unexplained fatigue—regardless of sleep quality—may indicate leukemia or lymphoma.
Postmenopausal Bleeding
While it may have benign causes, prolonged bleeding should prompt screening for uterine or cervical cancer.
Stomach Pain or Nausea
Persistent discomfort lasting over two weeks could signal liver, pancreatic, or digestive system cancers.
Unexplained Weight Loss
Fluctuations in weight are normal, but unintended weight loss or appetite changes may indicate advanced cancer.
Unusual Lumps
New lumps or masses that don’t go away should be checked. Swollen lymph nodes that persist after a cold or infection may need medical evaluation.
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