Aspirin use Linked to Improved Colon Cancer Survival

The majority of patients with colon cancer may benefit from taking aspirin after diagnosis

medwireNews: Taking aspirin may boost survival in patients with colon cancer whose tumours express human leukocyte Antigen (HLA) class I antigen, suggest study findings published in JAMA Internal Medicine.

The research examined tumour samples from 999 patients with stage I (13.8%), II (40.2%), III (28.7%) or IV (16.9%) colon cancer resected between 2002 and 2008. HLA class I antigen expression was confirmed in 66.8% of the 963 patients successfully assessed.

Overall, 19.0% of HLA-positive patients used aspirin after their colon cancer diagnosis and these patients had significantly longer overall survival than those who did not use aspirin, after adjusting for age, gender, tumour grade and stage, comorbidity and other factors (relative risk=0.53).

By contrast, the 18.0% of HLA-negative patients who used aspirin did not experience significant survival benefit compared with non-users, report Gerrit Jan Liefers, from the University Medical Center in Leiden, the Netherlands, and co-authors.

“Given that colon cancer in most of our cohort (>80%) was identified as stage III or less at the time of diagnosis, the predominant effect of aspirin on cancer outcomes is likely to result from an effect on circulating tumor cells and their ability to develop into metastatic deposits”, the authors say.

While the exact biological mechanism is not yet known, the researchers hypothesize that aspirin may combat metastases by inhibiting platelet–tumour cell signalling and preventing tumour cells making the epithelial–mesenchymal transition.

If these findings are confirmed, they could have significant implications for the use of aspirin in clinical practice, the team explains.

“First, low-dose daily aspirin may suffice as an antimetastatic therapy in patients with early-stage cancer”, write Gerrit Jan Liefers and co-authors. “Second, because circulating tumor cells are found in the perioperative period, it could be argued that aspirin therapy should be initiated as soon as considered clinically appropriate after diagnosis”.

In an accompanying commentary, Alfred Neugut, from Columbia University in New York, USA, notes that regular aspirin use has well known side effects including an increased risk of gastrointestinal and intracranial bleeding, and gastritis.

“However, in the setting of patients with stage III colon cancer, who have significant risks for mortality, the risks of a daily aspirin seem minor relative to the putative gains in mortality observed in the studies described herein”, he writes.

“Thus, this risk-benefit ratio would justify, until further studies are forthcoming, that tissue Biomarker studies are not necessary to define a subgroup to treat”.

References

Reimers M, Bastiaannet E, Langley R et al. Expression of HLA class I antigen, aspirin use, and survival after a diagnosis of colon cancer. JAMA Intern Med 2014; Advance online publication 31 March. doi:10.1001/jamainternmed.2014.511

Neugut A. Aspirin as adjuvant therapy for stage III colon cancer. Standard of Care? JAMA Intern Med 2014; Advance online publication 31 March 2014. doi:10.1001/jamainternmed.2013.14544

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