Gastrointestinal cancer-12-Rectal

GASTROINTESTINAL CANCER PART-12

Welcome to the 12th part of educational series on GastroIntestinal Cancers. We learned in part 11 about treatment of rectal cancer, including importance of locoregional treatment in form of chemoradiation. Also, the fact that most cancers in our country present at a stage when chemoradiation should be given before surgery, rather than after surgery. Preoperative treatment in this manner would also help to avoid colostomy in many cases.

Question: First of all Dr. Chiragbhai I am interested in outcome of patient discussed last week.

Answer: Sure. I am also happy to inform you that he underwent surgery in USA, which was completed in less than two hours, and most importantly a colostomy was avoided. Thanks to a very good response with chemoradiotherapy, enough surgical margin was achieved to avoid colostomy.

Que: But isn’t it difficult to operate after chemoradiation?

Ans: Thank you for bringing out an important question. This was the concern raised after initial very small studies. However, almost all large studies and clinical experience at most centers now is same as in patient mentioned above i.e. no increase in rate of complications, blood loss, duration of surgery etc. Surgery should be done preferably within 5-10 weeks after chemoradiation is completed. Experience at our center is same.

Que: Is chemoradiation today different than in past, resulting in better results?

Ans: Yes that is also true to some extent. As there are advances in radiotherapy machines and better trained radiation oncologists and physicists, there is significantly reduced toxicity. Also, we have learned a lot more about combining chemotherapy with radiotherapy. Best option used to be infusional 5-FU, which needs to be given continuously for 6 weeks i.e. patient has to wear an infusion pump and keep it on for 24 hours a day, for total 6 weeks. A good infusion pump costs over one lakh. Also, since this is practically very difficult, enough 5-FU was frequently not given in our country. Same can be now obtained with oral prodrug of 5-FU i.e. capecitabine, a markedly convenient and safer option. Also, other medicines can now be added to radiotherapy e.g. oxaliplatin.

Que: This sounds exciting, a prodrug of 5-FU?

Ans: Yes the same old 5-FU which is active in so many diseases, is now available as an oral form. This drug gets converted to 5-FU in tumor, using its own enzyme. Most of the western world, this has replaced IV 5-FU e.g. one of the regimens used in both colon and rectal cancers is FOLFOX, which requires three days of hospitalization every two weeks. Same can be easily achieved with CapeOx regimen, where patient comes for only a two hour infusion every three weeks, followed by oral capecitabine, without any hospitalization.

Of course, there are other advances as well in chemotherapy e.g. pharmacogenomics i.e. ability to predict drug side effect, thereby reducing dose in advance. Such tests are now available in India as well e.g. UGT1A1 polymorphism test helps to predict irinotecan toxicity, DPD/TS testing helps to predict 5-FU toxicity… There are tests for other medicines as well, which are rapidly becoming commercially available, as confirmatory studies are coming out. We discussed in earlier parts about tests to detect efficacy e.g. KRAS gene test to predict efficacy of Cetuximab.

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

Diplomate American Board of Oncology and Hematology. Ahmedabad. drchiragashah@gmail.com

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