Bowel Cancer

Disclaimer:
This blog is for informational purposes only and should not be taken as medical advice. Content is sourced from third parties, and we do not guarantee accuracy or accept any liability for its use. Always consult a qualified healthcare professional for medical guidance.

What is Bowel Cancer?

Bowel cancer, also known as colorectal cancer, originates in the colon or rectum, components of the large intestine. It typically begins as benign polyps (adenomatous or serrated) that can progress to malignancy over 5-15 years. Adenocarcinoma accounts for 95% of cases, with rare types including mucinous or signet-ring cell carcinoma. Stages range from 0 (carcinoma in situ) to IV (metastatic, often to liver/lungs). In 2025, colorectal cancer is the third most common cancer globally, with approximately 153,000 new US cases annually, affecting men and women nearly equally (median age 66).

Symptoms

Symptoms include blood in stool (bright red for rectal, dark for colon), persistent changes in bowel habits (diarrhea, constipation, or altered stool consistency lasting >3 weeks), abdominal discomfort (gas, bloating, cramps), a feeling of incomplete evacuation, unexplained weight loss, fatigue, nausea, vomiting, and anemia (especially iron-deficiency, causing pallor/breathlessness). Advanced disease may cause bowel obstruction, liver pain (from metastases), or rectal bleeding. Symptoms often mimic irritable bowel syndrome or hemorrhoids, delaying diagnosis by months.

Causes

Bowel cancer results from genetic and epigenetic alterations in colorectal cells, with key mutations in APC, KRAS, TP53, or PIK3CA. Risk factors include age (over 50), family history (10-15% of cases), inherited syndromes (e.g., Lynch syndrome, familial adenomatous polyposis [FAP]), inflammatory bowel disease (Crohn’s, ulcerative colitis), low-fiber/high-red-meat diets, obesity, smoking, heavy alcohol use, and type 2 diabetes. Protective factors include physical activity, high-fiber diets, and aspirin use in high-risk groups. In 2025, microsatellite instability (MSI-high, 15% of cases) and BRAF mutations are critical for prognosis and therapy selection.

Diagnosis

Screening is key, especially for those over 45, using fecal occult blood tests (gFOBT, FIT, detecting blood in stool), stool DNA tests (e.g., Cologuard, identifying genetic markers), or colonoscopy/sigmoidoscopy for direct visualization and polypectomy. Diagnostic confirmation involves colonoscopy with biopsy, assessing histology and molecular markers (KRAS, NRAS, BRAF, MSI). Imaging (CT, MRI, PET) evaluates local invasion and metastases, with CEA blood tests monitoring recurrence. In 2025, AI-assisted colonoscopy improves polyp detection by 30%, and liquid biopsies enhance metastatic screening.

Treatment

Localized disease (stages I-II) is treated with surgical resection (colectomy, polypectomy, or proctectomy), often curative without adjuvant therapy. Stage III or high-risk stage II cases add adjuvant chemotherapy (FOLFOX: 5-FU, leucovorin, oxaliplatin) to reduce recurrence by 20-30%. Metastatic disease (stage IV) uses systemic chemotherapy, targeted therapies (bevacizumab for VEGF, cetuximab/panitumumab for EGFR in RAS wild-type), and immunotherapy (pembrolizumab, nivolumab for MSI-high tumors, ~15% of cases). Radiation is used for rectal cancer. In 2025, nivolumab + ipilimumab is FDA-approved for dMMR colorectal cancer, achieving 55% response rates, and pivekimab sunirine shows promise in trials.

Future Outlook

In 2025, colorectal cancer’s 5-year survival is 65% overall, 90% for localized, 71% for regional, and 14% for metastatic disease. Advances in neoadjuvant immunotherapy, ADCs, and MSI-targeted therapies improve metastatic survival to 20-25%. Research focuses on mRNA vaccines, gut microbiome modulation, and AI-driven screening tools (reducing missed adenomas by 40%). By 2030, these could increase overall survival to 80% and metastatic to 30%, with emphasis on universal screening and personalized therapies for MSI-high and BRAF-mutant cancers.

Sources

The information for bowel cancer is sourced from the National Cancer Institute’s “Colon Cancer Treatment (PDQ®)” for comprehensive details on understanding, symptoms, causes, diagnosis, and treatment; Memorial Sloan Kettering’s “New Colorectal Cancer Treatments at MSK Aim To Reduce Deaths in 2025 and Beyond” for advancements in targeted and immunotherapy; Cancer Therapy Advisor’s “ASCO 2025: Advances in Colorectal Cancer” for clinical trial highlights; NCI’s “Immunotherapy Combo Approved for dMMR Colorectal Cancer” for new treatment approvals; and OncoDaily’s “Colon Cancer Cure Rate: What Patients Should Know in 2025” for prognosis and patient-focused updates.