Source: National Cancer Centre Singapore, 2010 Media Release

Oncologists at the National Cancer Centre Singapore (NCCS) are undertaking a mammoth task of leading an investigator-initiated multi-centre phase III clinical trial across Asian countries to evaluate the efficacy of Aspirin in reducing the risk of recurrence of colorectal cancer post surgery and chemotherapy.

Colorectal cancer, the third most common cancer worldwide, has claimed the lives of many and will continue to do so as cancer incidence rates in Asia continue to rise. New therapies are urgently needed to tackle this disease – and these treatments need to be not only effective, but affordable as well.

Many drugs, in the past 15 to 20 years, have been evaluated in an attempt to improve outcomes for patients with stage II and III colorectal cancer. However, with exception to oxaliplatin chemotherapy, no other agent has been shown to improve patient survival. These include costly targeted therapies, which although highly active in the metastatic setting, do not seem to provide benefit when used in stage II and III disease.

It is unimaginable 10 years ago that Aspirin could have potential as an anti-cancer drug but not so today. In the past year, Aspirin has piqued the interest of the scientific community, since the publication of several articles that seem to suggest patients with colorectal cancer (and even breast cancer) who were started on Aspirin had a significant reduction in the risk of recurrence and death, compared to those who were not on it.

There is a strong biological basis as to why Aspirin may work in colorectal cancer. Abnormal inflammation appears to be a driver of tumour growth in many cancers types and several studies have correlated high blood inflammation markers with a higher cancer relapse risk. Although some studies lend strong indirect support, no randomised trial has ever been conducted so far to provide a definite answer as to whether Aspirin really works.

Developing any new drug for cancer is a complex and expensive business. New drugs always have to be directly compared against standard treatment in a clinical trial setting. It involves substantial numbers of patients who need to be followed up for many years. Although difficult to do, these studies are still worth doing because it have the potential to change how medicine is practiced.

"Aspirin costs a mere three cents a tablet. Imagine the impact and the number of lives we could potentially save in the developing and developed world if the trial is proven beneficial using such a low cost drug with a wide ranging reach," said Dr Toh Han Chong, Head of the Medical Oncology Department at NCCS.

"This study outcome may change everyday clinical practice worldwide and impact the management of stage III and some stage II colorectal cancer globally," added Dr Toh.

However, to succeed in a trial of this magnitude, it would require the establishment of a strong and large clinical trial network. To date, NCCS has set up a network of 19 centres across Asia including Malaysia, Hong Kong, Indonesia, the Philippines, China and India, and more centres are currently lined up to join the study.

"Unlike the West, our experience of running phase III clinical trials is limited," said Dr John Chia, also a medical oncologist at the NCCS.

"We are trying to build a community of like-minded research-focused individuals who are willing to devote their time to answer this question, and who will be willing to share the collective intellectual ownership of this clinical trial. Eventually, by establishing this network, we hope to build a foundation that will enable us to perform future clinical trials. This will enable us to answer clinical questions relevant to our local communities. As Asia modernises, we should not constantly rely only on trials designed in the West."

This clinical trial is open to accrual in Singapore. After completion of standard surgery and chemotherapy, patients with high risk stage II or stage III colorectal cancer will be given either Aspirin or a placebo for a period of three years and be followed up intensively for recurrence over a period of five years.

Although the supporting evidence for Aspirin is highly encouraging, it is still by no means conclusive and will have to be proven in the phase III trial.

Both oncologists cautioned against jumping the gun and warned patients against taking Aspirin outside of the clinical trial because the drug thins the blood and can increase one's risk of bleeding. Patients who wish to take Aspirin for colorectal cancer need to be closely monitored and consume it only under strict supervision.