Colon Cancer

Colon cancer affects about 1 person in 20 and, while highly curable in its earliest stages, is the second leading cause of death from malignant disease in the western world. Although usually preceded by an easily recognized pre-malignant lesion, a polyp, diagnosis is often not made until late in the disease. The development of colon cancer seems to be associated with a diet rich in animal fats and low in fiber and calcium. Personal risk factors for developing colon cancer include: age over 50, a history of inflammatory bowel disease, a history of colon polyps, or having a close family member with colon cancer.

Regular colon screenings through colonoscopy are recommended for people over the age of 50. When undergoing regular cancer screenings, if a cancer is diagnosed, even when that cancer is invasive, it is found in its early stages and a cure is likely. Three facts about colon cancer are worth enumerating here. Fact one, 90% of all colon cancers found during routine screening colonoscopies are cured. Fact two, 90% of colon cancers arise from acquired genetic mutations and occur in people over the age of 50, the age at which routine screening-colonoscopies should commence. Fact three, more than 80% of all colon cancers should be prevented or cured if all at risk individuals, which means everyone upon turning 50, underwent screening. The simple math is overwhelming. If routine colon cancer screening guidelines were followed, more than 80% of colon cancer deaths would be avoided.

For more in depth information, please read Colon Cancer Answers by Dr. Bruce Feinberg.

Colon Cancer Treatment Summaries

Stage II

While chemotherapy for stage II disease is not routine, recent national guidelines have revised recommendations for adjuvant chemotherapy in stage II disease. While overall stage II disease has a 70-80% overall survival, this may not be seen in “poor prognosis” stage II disease. Adjuvant chemotherapy is likely to provide an approximate 5% overall improved survival in stage II disease, and should be considered in the following cases:

Suboptimal lymph node sampling-current recommendations are to sample at least 13 nodes.
T4 disease
Lympho/vascular invasion
Bowel obstruction at time of diagnoses
Colonic perforation at site of tumor.

Adjuvant chemotherapy may consist of single agent 5-FU or capecitabine for lower risk patients, with FOLFOX considered in higher risk patients.

References

Benson A., et al. American Society of Clinical Oncology Recommendations on Adjuvant Chemotherapy for Stage II Colon Cancer. JCO 22(16):3408-3410, 2004.

Stage III

The use of adjuvant chemotherapy is considered standard of care for stage III colorectal cancer. An approximately 30-40% reduction in the risk of recurrence is expected with a standard 6 month course of therapy. Recent data has indicated an additional 20% relative improvement when oxaliplatin is added to 5-FU based adjuvant chemotherapy.(1) For patients with poor performance status or significant comorbidities, single agent 5-FU or oral capecitabine is also a reasonable option. (2) The role of targeted therapies such as bevacizumab in the adjuvant setting is unknown, but clinical trials are actively investigating this question.

References:

Andre T., et al. Oxaliplatin, Fluorouracil and Leucovorin as Adjuvant Treatment for Colon Cancer. NEJM 350: 2343-51 (2004).
Twelves C., et al. Capecitabine as Adjuvant Treatment for Stage III Colon Cancer. NEJM 353:2696-2704, 2005.

Metastatic colorectal cancer

Metastatic Colorectal Cancer:
D. Carr, MD

The survival of patients with metastatic colorectal cancer has improved as a result of sequential treatment with combinations of the 3 active drugs 5FU, Irinotecan, and Oxaliplatin. Recent phase III studies indicate that whereas fluoropyrimidine monotherapy results in median survivals of approximately 12 months, sequential Irinotecan plus 5FU/LV followed at progression by Oxaliplatin plus 5FU/LV, or the reverse sequence of these regimens, received either de facto or by study design, yields median survivals of 20-22 months (1). Either sequence appears to yield approximately equivalent benefits (2).

Subsequent to these advances, active monoclonal antibodies have been introduced. The combination of the antiangiogenic agent Bevacizumab with 5FU-based combination chemotherapy as initial therapy has resulted in significant survival improvement over chemotherapy alone (3) with median overall survival exceeding 2 years; such combinations have now become the standard of care for patients with MCRC. The epithelial growth factor receptor inhibitor Cetuximab overcomes tumor resistance to Irinotecan in previously Irinotecan-refractory patients (4); its contribution survival benefit in the relapsed patient, and role in first-line therapy have not been fully assessed and are the subjects of ongoing clinical trials.