August 17, 2015

expert reaction to study on the effect of aspirin on Lynch Syndrome sufferers’ risk of cancer

Attempting to investigate the association between body mass index and cancer risk in patients with lynch syndrome, a team of researchers have published their work in the journal of Clinical Oncology. They report that obesity is associated with a substantial increase in risk of developing colorectal cancer in patients with lynch syndrome, but this risk is reduced in those taking aspirin.

Dr Mangesh Thorat, Research Fellow, Centre for Cancer Prevention, Queen Mary University of London, said

“Aspirin has shown cancer prevention benefits at various doses, including doses well below 100 mg per day typically used for prevention of cardiovascular events. It appears to act through several different mechanisms in preventing cancer development and spread of cancer cells; some of these may be active only at specific doses. These results from CAPP2 trial of 600 mg per day aspirin in individuals with Lynch syndrome provide a hint that some of aspirin’s actions cause reversal of effects of excess weight and thereby prevent development of colorectal cancer in these individuals.

“The magnitude of difference is not very large and these findings are based on a very select population using a rather high aspirin dose. Therefore, although scientifically interesting, these results should be considered as hypothesis generating. Further studies to see whether a similar benefit is also seen in the general population are needed.

“Furthermore, the adverse effects of aspirin, especially gastro-intestinal bleeding are more likely at higher doses, and overweight or obese individuals are already at a higher risk of bleeding. Therefore, use of aspirin at this dose cannot be currently recommended for colorectal cancer prevention in the general population.”

Prof. Jack Cuzick, Director of the Wolfson Institute of Preventive Medicine and Head of the Centre for Cancer Prevention, Queen Mary University of London, said:

“While the link between obesity and colorectal cancer benefit of aspirin remains speculative at this stage, especially as there was no link with being overweight but not obese,  there is clear evidence from a range of studies (summarized in Cuzick et al, Estimates of benefits and harms of prophylactic use of aspirin  in the general population, Annals of Oncology, 2015,26:47-57), that most people aged 50-65y would benefit from taking a daily low dose aspirin (less than 100mg) for 5-10 years. This reduces both incidence and death from colorectal, stomach, and oesophageal cancer by about a third and also reduces breast, prostate and lung cancer by a smaller amount.

“However, the robustness of this research was limited by the fact that it was a finding from a retrospective exploratory subgroup, and so further research is needed to independently confirm whether cancer risk was reduced only in obese patients but not overweight or normal weight patients. ”

‘Obesity, Aspirin, and Risk of Colorectal Cancer in Carriers of Hereditary Colorectal Cancer: A Prospective Investigation in the CAPP2 Study’ by Movahedi et al. will be published in Journal of Clinical Oncology at 21:00 UK time on Monday 17 August, which is also when the embargo will lift. 

Declared interests

Dr Mangesh Thorat: No conflicts of interest but see disclosures below.

Disclosures:

Prof. John Burn, Chief Investigator of CAPP2 is a co-author on one of our aspirin papers (http://annonc.oxfordjournals.org/content/26/1/47 )

Executive Board member of International Society of Cancer Prevention (ISCaP). ISCaP received an educational grant from Bayer for organising 8^th International Conference on Gastrointestinal Cancer Prevention in 2014.

Prof. Jack Cuzick is on the advisory board for Bayer (paid, but not regular).