Rectal cancer is a type of cancer that begins in the rectum, the last several inches of the large intestine1 . Early-stage rectal cancer often does not cause symptoms, making screening essential for early detection and improved outcomes2 . The incidence of colorectal cancer in adults under 50 has more than doubled since the 1990s, leading to updated screening guidelines recommending screening start at age 453 . Recognizing symptoms early and seeking timely medical evaluation can significantly improve treatment success and survival rates2 .
Early Warning Signs
Early rectal cancer and its precursors, such as rectal polyps, often do not cause symptoms and may be found only through screening2 . Polyps are abnormal tissue growths on the mucous membrane of the rectum, and some types, especially adenomatous polyps, can develop into cancer over time2 . Symptoms usually appear as the tumor grows and invades surrounding tissues2 .
Blood in Stool
Rectal bleeding is the most common initial symptom reported by patients with rectal cancer2 . This bleeding may be visible as bright red blood on or in the stool, often indicating bleeding from the distal colon or rectum2 . However, rectal bleeding is not specific to cancer and can also result from benign conditions such as hemorrhoids or anal fissures2 . Unlike hemorrhoidal bleeding, which tends to be intermittent, cancer-related bleeding is often continuous or progressively worsening2 . Occult bleeding, which is not visible to the naked eye, can be detected by fecal occult blood tests used in screening2 .
Painful Bowel Movements
Pain or discomfort during bowel movements can be an early warning sign of rectal cancer4 . This may include pain in the rectal area or a sensation of discomfort when sitting. Such symptoms may arise as the tumor grows and irritates the rectal lining or surrounding tissues2 .
Changes in Bowel Habits
Changes in bowel habits are common early symptoms of rectal cancer and may include diarrhea, constipation, or a more frequent need to pass stool1 . Patients may also notice stools that are narrower than usual or a sudden change in how and when they have bowel movements5 . These changes result from the tumor partially blocking the rectal passage or affecting bowel function2 . A persistent change lasting more than a few days should prompt medical evaluation6 .
Incomplete Bowel Emptying
A feeling that the bowel does not empty completely after a bowel movement is another symptom associated with rectal cancer7 . This sensation may be due to tumor growth causing obstruction or irritation in the rectum1 . Patients may also experience a persistent urge to have a bowel movement that is not relieved by passing stool6 .
Rectal cancer can be challenging to detect because you may feel only slight symptoms or even none at all. By the time symptoms like rectal bleeding or changes in bowel habits appear, the cancer may be more advanced. Regular screening based on age and risk factors is critical for early detection8 .
Advanced Symptoms
As rectal cancer progresses, symptoms tend to worsen or new symptoms appear due to tumor growth, local invasion, or systemic effects2 . These include unexplained weight loss, anemia, fatigue, abdominal pain, and urinary symptoms.
Unexplained Weight Loss
Unintentional weight loss is a common systemic symptom in advanced rectal cancer2 . This results from cancer cachexia, a complex metabolic syndrome involving increased glucose consumption by tumor cells, systemic inflammation, and breakdown of fat and muscle tissue to meet energy demands9 . Pro-inflammatory cytokines released during cancer contribute to metabolic changes and muscle wasting, exacerbating weight loss9 . Additionally, tumor-related symptoms such as pain or obstruction can reduce appetite and food intake2 .
Anemia
Chronic blood loss from the tumor can lead to anemia, characterized by a low red blood cell count6 . This may cause symptoms such as pale skin, shortness of breath, and dizziness. Anemia in rectal cancer patients often results from bleeding into the digestive tract, either visible or occult6 .
Fatigue
Fatigue is a frequent symptom in patients with rectal cancer and is often related to anemia, systemic inflammation, and the overall metabolic burden of the disease6 . Patients may feel unusually weak or tired even with minimal exertion5 .
Abdominal Pain or Cramping
Abdominal pain or cramping may occur as the tumor grows and causes obstruction or irritation in the lower abdomen2 . This pain can be persistent or intermittent and may be accompanied by bloating or a feeling of fullness4 .
Urinary Symptoms
Although less common, urinary symptoms may arise if the tumor invades or compresses adjacent structures near the rectum, such as the bladder2 . These symptoms can include difficulty urinating or increased frequency.
- Common advanced symptoms of rectal cancer include:
- Unexplained weight loss due to cancer cachexia9
- Anemia from chronic blood loss6
- Fatigue related to anemia and systemic effects5
- Abdominal pain or cramping from tumor growth2
- Urinary symptoms from local invasion2
Late-Stage Symptoms
In late-stage rectal cancer, the disease often spreads (metastasizes) to other organs, causing additional symptoms related to the affected sites2 .
Jaundice
Jaundice is characterized by yellow discoloration of the skin and the whites of the eyes (sclera) due to elevated bilirubin levels in the blood2 . Liver metastases from rectal cancer can impair the liver's ability to process bilirubin, leading to its accumulation2 . Jaundice is often accompanied by dark urine and clay-colored stools due to altered bile flow2 .
Back Pain
Bone metastases from rectal cancer can cause localized pain, often in the spine or pelvic bones2 . This metastatic bone pain may be intermittent or persistent and should prompt urgent medical evaluation if new or worsening2 .
Pelvic Pain
Local invasion of adjacent pelvic structures is common in advanced rectal cancer and can cause pelvic pain2 . The pelvis is the area between the hip bones that contains the rectum and other organs2 . Pelvic pain may be continuous or occur with certain movements or activities.
Other Symptoms
Other late-stage symptoms may include systemic signs such as weakness, fatigue, and symptoms related to metastases in other organs2 . These symptoms indicate advanced disease and often require multimodal treatment approaches2 .
Jaundice and bone pain are warning signs of metastatic rectal cancer. If you experience yellowing of the skin or new back pain, seek prompt medical attention to evaluate possible cancer spread2 .
Symptoms in Young Adults
The incidence of early-onset colorectal cancer (EO-CRC), defined as colorectal cancer diagnosed before age 50, has risen significantly in recent decades3 1011. This increase has led to recommendations to begin colorectal cancer screening at age 45 for average-risk adults3 1011.
Young adults with rectal cancer often present with red-flag symptoms up to two years before diagnosis3 . The presence of even a single red-flag symptom nearly doubles the risk of EO-CRC, and multiple symptoms substantially increase the likelihood of diagnosis3 . These symptom-risk correlations are particularly strong in younger patients and those with rectal cancer3 .
Common symptoms in young adults mirror those in older patients and include rectal bleeding, changes in bowel habits, abdominal pain, and unexplained weight loss9 11. Early evaluation of these symptoms in younger adults is critical to facilitate timely diagnosis and treatment3 .
- Key points about rectal cancer symptoms in young adults:
- EO-CRC incidence has more than doubled since the 1990s10 11
- Screening now recommended starting at age 453 1011
- Red-flag symptoms often appear up to two years before diagnosis3
- Single or multiple symptoms increase EO-CRC risk substantially3
- Early symptom recognition improves outcomes in younger patients3
When to See a Doctor
Prompt medical evaluation is essential if you experience any symptoms suggestive of rectal cancer. Rectal bleeding, changes in bowel habits lasting more than a few days, unexplained weight loss, or persistent abdominal pain should not be ignored2 8.
Many gastrointestinal symptoms have benign causes, but early assessment can help rule out serious conditions like rectal cancer2 . Screening programs have significantly reduced colorectal cancer mortality by detecting early lesions before symptoms develop2 . Current guidelines recommend colorectal cancer screening start at age 45 for average-risk adults, with high-risk individuals advised to begin earlier2 .
- Seek medical advice if you experience:
- Rectal bleeding or blood in the stool2
- Persistent changes in bowel habits (diarrhea, constipation, narrow stools) 6
- Unexplained abdominal pain or cramping2
- Unintended weight loss or fatigue5
- A feeling of incomplete bowel emptying or persistent urge to defecate7
“If rectal cancer is caught in the early stages, the prognosis is very favorable, with a cure rate of over 80%. Once the cancer spreads to the surrounding tissue, it is much more difficult to treat. Early intervention is key, so if you are experiencing any of the symptoms mentioned above, make an appointment with your doctor to discuss your concerns.”
— Tori-Lynn Pacelle, UConn Health12
Key Takeaways
- Rectal cancer often begins as small polyps that may not cause symptoms until they grow larger2 .
- The most common early symptom is rectal bleeding, but it can also be caused by benign conditions like hemorrhoids2 .
- Changes in bowel habits, painful bowel movements, and a feeling of incomplete emptying are important early warning signs1 7.
- Advanced disease may cause systemic symptoms such as unexplained weight loss, anemia, fatigue, and abdominal pain9 2.
- Late-stage rectal cancer can spread to the liver and bones, causing jaundice and back pain, respectively2 .
- The incidence of rectal cancer in young adults is rising, making early symptom recognition and screening critical3 10.
- Timely medical evaluation of symptoms improves diagnosis and treatment outcomes2 .
Common Questions
What are the first signs of rectal cancer?
The earliest signs often include rectal bleeding, changes in bowel habits such as diarrhea or constipation, and a feeling that the bowel does not empty completely2 1.
Can rectal cancer cause pain?
Yes, painful bowel movements and abdominal cramping can occur as the tumor grows and irritates surrounding tissues2 4.
Is rectal bleeding always cancer?
No, rectal bleeding can result from benign causes like hemorrhoids or anal fissures, but persistent or worsening bleeding should be evaluated by a healthcare provider2 .
Why is rectal cancer increasing in young adults?
The reasons are not fully understood, but the incidence of early-onset colorectal cancer has more than doubled since the 1990s, prompting earlier screening recommendations3 10.
How important is screening for rectal cancer?
Screening is crucial as early-stage rectal cancer may not cause symptoms. Early detection through screening significantly improves treatment success and survival2 8.
