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Gastrointestinal cancer-9-Colon


Welcome to the ninth part of educational series on GastroIntestinal Cancers. We learned in part 8 about etiology, family history and early diagnosis of colon cancer.

Question: Now Dr. Chiragbhai, how do you treat colon cancer?

Answer: Treatment can be divided according to early and late stages.

For stage 1 to 3, primary treatment is surgery, basically hemi colectomy with good regional lymph node dissection. Once again, this should be done by a trained surgeon who routinely operates on colon cancer. Intra operative evaluation should include assessment of synchronous primary or metastatic disease, especially in liver and peritoneum.

Role of pathologist is also very important. Therefore, cancer histopathology experience is equally important. A good pathology review is first step in assessing quality and adequacy of surgery. Most important is to assess all margins of surgical resection, number of nodes involved, grade of tumor, lymphovascular invasion, other signs of local spread e.g. nodules in pericolic fat. Number of nodes evaluated is so important, that if there are less than 12 nodes evaluated (either not resected or not evaluated by pathologist), it is considered as incomplete resection. Such patients are given adjuvant chemotherapy as if they have positive nodes.

Que: It is interesting to note this very important role of pathologist. What is the role of other modalities in colon cancer?

Ans: Adjuvant therapy in the form of chemotherapy is very important. Role of radiotherapy is limited, only rarely required in colon cancer, however very important in rectal cancer, as we will see later.

Que: Are there any important advances in chemotherapy?

Ans: Colon cancer used to be treated by only 5-FU and Leucovorin for many years. However, in last decade there have been many new medicines, with improved efficacy and more importantly tolerability and convenience.

Adjuvant chemotherapy improves survival by about 10%-20% absolute, depending upon stage and number of positive nodes. This is very important, compared to what we achieve in other common diseases. For example, streptokinase in acute myocardial infarction improves survival by absolute 2% and primary angioplasty (PAMI) by about 4-6% at best.

5-FU/LV is still important backbone of many regimens, but addition of oxaliplatin has improved results significantly, as seen in MOSAIC trial. Capecitabine is an oral drug, which converts to 5-FU directly in tumor. This allows oral treatment, which is very convenient for patients. We have switched to use of oral treatment in over 90% of our patients, and rarely use intravenous 5-FU nowadays.

New monoclonal antibodies like Avastin (bevacizumab) and Erbitux(cetuximab) have shown significant activity in metastatic disease, and are being evaluated in adjuvant/postoperative therapy.

Dr. Chirag A. Shah; M.D. Oncology/Hematology (USA), 98243 12144, 98988 31496

Diplomate American Board of Oncology and Hematology. Ahmedabad.

Shyam Hem-Onc Clinic. 402 Galaxy, Near Nehrunagar Circle, Ahmedabad.