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Adjuvant Therapy for completely resected Stage II Colon Cancer

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Abstract

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Background

: Colon cancer is potentially curable by surgery. Although adjuvant chemotherapy benefits patients with stage III disease, there is uncertainty of such benefit in stage II colon cancer. A systematic review of the literature was performed to better define the potential benefits of adjuvant therapy for patients with stage II colon cancer.

Objectives

: To determine the effects of adjuvant therapy on overall survival and disease‐free survival in patients with stage II colon cancer.

Search methods

: Ovid MEDLINE(R) (1986‐2007), EMBASE (1980‐2007), and EBM Reviews ‐ Cochrane Central Register of Controlled Trials ( to 2007) were searched using the medical headings "colonic neoplasms", "colorectal neoplasms", "adjuvant chemotherapy", "adjuvant radiotherapy" and "immunotherapy", and the text words "colon cancer" and "colonic neoplasms". In addition, proceedings from the annual meetings of the American Society of Clinical Oncology and the European Society of Medical Oncology (1996 to 2004) as well as personal files were searched for additional information.

Selection criteria

: Randomized trials or meta‐analyses containing data on stage II colon cancer patients undergoing adjuvant therapy versus surgery alone.

Data collection and analysis

: Three reviewers summarized the results of selected studies. The main outcomes of interest were overall and disease‐free survival, however, data on toxicity and treatment delivery were also recorded.

Main results

: With regards to the effect of adjuvant therapy on stage II colon cancer, the pooled relative risk ratio for overall survival was 0.96 (95% confidence interval 0.88, 1.05). With regards to disease‐free survival, the pooled relative risk ratio was 0.83 (95% confidence interval 0.75, 0.92).

Authors' conclusions

: Although there was no improvement in overall survival in the pooled analysis, we did find that disease‐free survival in patients with stage II colon cancer was signficantly better with the use of adjuvant therapy. It seems reasonable to discuss the benefits of adjuvant systemic chemotherapy with those stage II patients who have high risk features, including obstruction, perforation, inadequate lymph node sampling or T4 disease. The co‐morbidities and likelihood of tolerating adjuvant systemic chemotherapy should be considered as well. There exists a need to further define which high‐risk features in stage II colon cancer patients should be used to select patients for adjuvant therapy. Also, researchers must continue to search for other therapies which might be more effective, shorter in duration and less toxic than those available today.

Plain language summary

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Adjuvant therapy for completely resected stage II colon cancer

Colon cancer is the second most common cause of cancer deaths in the Western world. A large proportion of colon cancer patients can be cured by surgical resection alone. For those patients with lymph node positive (stage III) disease, the recurrence rate can exceed 50% and adjuvant chemotherapy has been shown to significantly reduce the risk of recurrence. In patients without lymph node involvement (stage I and II), the prognosis is quite good with surgery alone, with survival rates of 75% to 95% at 5 years. However, some patients with high risk stage II disease have a relapse rate approaching that of stage III colon cancer patients. Due to the effectiveness of systemic chemotherapy in stage III disease, a similar approach has been considered for patients with stage II disease. We performed a systematic review looking at all randomized clinical trials evaluating stage II colon cancer patients and adjuvant therapy versus surgery alone. Our review found that adjuvant therapy ‐either systemic or regional chemotherapy or immunotherapy‐ can improve the outcomes of stage II patients. In counselling individual patients, the advice given should be conditioned by the patient's age and comorbidities. In addition, the high risk features of the tumour should also be considered when contemplating the benefits of systemic therapy in patients with stage II colon cancer. Further investigation is needed to elucidate which patient and tumour factors can be used to select stage II colon cancer patients for adjuvant therapy. There also exists a need to continue to search for other adjuvant therapies which might be more effective, shorter in duration and less toxic than those available today.