I absolutely agree with Santam and Inranil, Ph 1 = 45 Gy/25#/ 5 week and Ph= 2 5.4 Gy / 3 #
1. German rectal cancer Study group (Sauer et al) used 50.4 Gy as mentioned above and the volumes were as described by Santam.
2. NSABP R-03 also used same doses and volumes like the Germans
3. RTOG Ph 2 trials which Indranil has provided also used Boost doses
4. EORTC 22921 trial [largest trial with 1111 pts used only 45 Gy (ph 1) No Boost.
5. FFCD 9203 also used 45 Gy (Ph 1) only.
A cochrane meta-analysis http://www.ncbi.nlm.nih.gov/pubmed/19160264
This Meta-analysis showed complete pathologic response (11.8 versus 3.5 %) and improvement in local control (16.5 versus 9.4 %) but had no significant impact on rates of sphincter preservation, disease-free survival, or overall survival.
Literature review suggests use of 45 -50.4 Gy of RT in combination with chemo (5FU based), however if you look at this issue carefully, it is difficult to know what is the benefit of the boost ? which is the million dollar question.
The argument Against its use is based on the fact, THE EUROPEAN PERSPECTIVE
1. that the surgeon is going to chop off and do a good TME (Total mesorectal excision), so why bother with the boost.
2. Toxicity (Gr3 & 4) is nearly 15% from meta-analysis so a theoritical assumption that toxicity would be less with 45 Gy compared to 50.4 Gy --- common sense perhaps.
The arguments For its use are predominantly may be, THE AMERICAN PERSPECTIVE
1. The higher the incidence of pCR , the better is the outcome
2. Data from clinical trials, protocol based have demostrated clinical efficacy with acceptable toxicity.
Wonder anybody in the forum has any strong feelings For and Against a Boost.
ANY INDIAN PERSPECTIVE
abhinavahluwalia, 15 Aug 2010 13:22