Aspirin trial seeks to tackle colorectal cancer in Asia

Medical Tribune September 2009 P8
David Brill

A major new trial is set to launch in Asia to establish whether aspirin can prevent recurrence of colorectal cancer.

The ASCOLT study will involve over 2,000 patients from centers across Southeast Asia, China and India, and will be led jointly by the National Cancer Centre Singapore (NCCS) and the University of Oxford, UK.

Patients will be randomized to aspirin (200mg/day) or placebo for 3 years, following surgery and adjuvant chemotherapy for high-risk stage II and III colorectal cancer. The primary endpoint will be disease-free survival over 5 years of follow-up.

A growing body of evidence suggests that aspirin is effective for primary prevention of colorectal cancer, but ASCOLT is thought to be the first prospective clinical study to investigate the drug in the adjuvant setting after chemotherapy.

If positive, the results could have a huge impact on the treatment of colorectal cancer in Asia and worldwide, according to Dr. Toh Han Chong, head of the department of medical oncology at NCCS and one of the ASCOLT lead investigators.

“It’s incredible how many people you could save from relapse with the addition of aspirin if this study is positive. If you go to a village in India you can’t really give costly [monoclonal antibodies], so there is compelling power of social responsibility here,” he told Medical Tribune.

“We have undervalued the power of simple drugs. It’s time to redress the balance – change the paradigm and go cheap.”

Recruitment for ASCOLT is already underway, with centers confirmed in Singapore, Hong Kong, Jakarta and several cities in India.

More study centers are still needed in order to reach the target of 2,000 patients however said Toh, who extended the invite to all Asian delegates at the recent ‘Best of ASCO’ conference in Singapore.

“It’s a drug trial that cannot be done in the West. Many people over the age of 50 in the US are popping aspirin over the counter for heart conditions or stroke prevention,” he said. “Fewer people are on aspirin in Asia. That’s why it’s a perfect study to do here.”

Colorectal cancer is the second leading cause of cancer death in North America, Europe and Australasia according to a 2007 global report from the American Cancer Society. In Southeast Asia, it is the third biggest killer (behind liver and lung cancer) – responsible for 7.9 percent of cancer deaths.

In Singapore, colorectal cancer is the leading cancer among men and the second most common among women, data from the national cancer registry show.

A recent study found that regular use of aspirin after a diagnosis of colorectal cancer was associated with lower overall mortality (hazard ratio [HR] 0.79; 95% CI 0.53 – 0.95) and cancer-specific mortality (HR 0.71; 0.53 – 0.95), after a median of 11.8 years of follow-up. [JAMA 2009;302(6):649-58]

A 2007 paper, meanwhile, reported that taking 300 mg/day or more of aspirin for 5 years was effective for primary prevention of colorectal cancer, according to pooled data from two large randomized trials (HR 0.74; 95% CI 0.56 – 0.97; P=0.02). [Lancet 2007;369(9573):1603-13] Earlier trials have also shown that aspirin can prevent colorectal adenomas – the precursors to cancer – both in patients with, and without, a prior history of cancer. [N Engl J Med 2003;348(10):883-90; N Engl J Med 2003;348(10):891-9]

“Why should oncologists do an aspirin trial? Because the epidemiological data is strong, the data on polyp reduction is very convincing, the retrospective observational studies are very compelling and remarkable in terms of hazard ratios, and the data preclinically is scientifically robust,” added Toh.