What is rectal cancer?
Rectal cancer is a type of cancer that develops in the rectum — the final part of the large intestine, approximately 12-15 cm long, which connects the sigmoid colon to the anus. Although it is often grouped with colon cancer under the general term “colorectal cancer,” rectal cancer has important particularities in terms of diagnosis, treatment and recovery.
A tumor found in the first 15 cm from the anal verge is classified as a rectal tumor, while those located higher are considered colon tumors. This distinction is important because treatment differs significantly.
How common is it?
Colorectal cancer is the most common cancer in Europe and the third most common worldwide. Approximately one third of colorectal cancers are located in the rectum. Colorectal cancer is more common in men than in women. Most patients are over 60 years old at diagnosis, and disease under age 40 is rare — though cases in younger patients are rising.
The incidence of colorectal cancer is higher in industrialized and urbanized regions, suggesting an important role for environmental and lifestyle factors.
Anatomy of the rectum
The rectum is divided into three thirds, and the location of the tumor directly influences treatment strategy:
- Upper third (12-15 cm from the anal verge) — tumors in this area behave more like colon tumors
- Middle third (7-12 cm from the anal verge) — usually requires neoadjuvant treatment
- Lower third (0-7 cm from the anal verge) — treatment differs significantly, with implications for sphincter preservation
The rectum is surrounded by the mesorectum — fatty tissue containing lymph nodes and blood vessels. Complete removal of the mesorectum during surgery (TME) is essential for an optimal oncologic outcome.
Risk factors
A risk factor increases the likelihood of cancer occurring, but is neither necessary nor sufficient to cause the disease. Some people with risk factors will never develop cancer, and others without risk factors may still be diagnosed.
Approximately 80% of colorectal cancers are sporadic (not linked to inherited genes). About 20% occur in a familial context, and less than half of these are caused by a known hereditary syndrome.
Main risk factors
- Age — risk increases significantly after age 50, although cases in younger patients are rising
- Diet — a diet high in red meat (beef, pork, lamb), processed meat, fats and low in fiber increases risk. Excessive alcohol consumption is also a risk factor
- Obesity — being overweight independently increases risk
- Sedentary lifestyle — lack of physical activity, independent of body weight
- Type 2 diabetes — increases risk independently of weight
- Smoking — increases the risk of developing large colorectal polyps, which are precancerous lesions
- History of colorectal polyps — polyps (adenomas) are not cancerous, but can transform into cancer over several years. When discovered, they should be removed
- Personal history of colorectal cancer — even after complete treatment, there is an increased risk of developing a new tumor
- Inflammatory bowel diseases — ulcerative colitis and Crohn’s disease cause chronic inflammation that can progress to dysplasia and then cancer. Risk increases with duration and severity of disease
- Family history — if a first-degree relative has colorectal cancer, your risk is doubled
Hereditary syndromes
- Familial adenomatous polyposis (FAP) — mutation of the FAP gene that causes hundreds or thousands of polyps in the large intestine from a young age. Cancer can develop before age 40
- Lynch syndrome (HNPCC — Hereditary Non-polyposis Colorectal Cancer) — genetic mutations affecting DNA repair mechanisms. A benign polyp can transform into cancer much faster (2-3 years). Average age at diagnosis is 45 years
Investigating a possible family history is important. In selected cases, screening at a young age and/or genetic counseling should be considered.
Protective factors
- A diet rich in vegetables, fruit and whole grains lowers risk
- Regular physical activity can reduce risk
- Long-term aspirin — has been shown to reduce risk in people with Lynch syndrome and may prevent recurrence of non-hereditary polyps
Symptoms
Rectal cancer can be asymptomatic in the early stages. Symptoms that should prompt you to see a doctor include:
- Rectal bleeding — bright red blood in the stool or on toilet paper
- Changes in bowel habits — diarrhea, constipation, or alternating between them
- Thin (ribbon-like) stools
- Tenesmus — sensation of incomplete evacuation after defecation
- Abdominal or pelvic pain
- Unexplained weight loss
- Fatigue and anemia
Important: These symptoms can also occur in other conditions (hemorrhoids, anal fissures, inflammatory bowel disease). Only a doctor can establish the correct diagnosis through appropriate investigations.
When to see a doctor
Consult a gastroenterologist or colorectal surgeon if:
- You have persistent rectal bleeding
- You notice changes in bowel habits lasting more than 2-3 weeks
- You have a family history of colorectal cancer
- You are over 45 and have never had a screening colonoscopy
Early diagnosis significantly improves prognosis and treatment options.