Thromboembolism during neoadjuvant therapy for rectal cancer: a systematic review

Abstract

Aim: Thromboembolism (TE) is a common, costly and morbid complication that is also associated with decreased survival in cancer patients. However, the risk of cancer-associated TE varies because of the multitude of patient-, cancer- and treatment-related influences. Thromboprophylaxis (TP) is currently not widely adopted in the ambulant population. A review of the literature was undertaken to determine the rate of TE and the benefit of TP in patients with rectal cancer during neoadjuvant therapy (nT).

Method: A systematic literature search of electronic databases, including PubMed and Embase, was performed (1995-2012) for all studies assessing nT in rectal cancer. Data were extracted and used to assess study design, patient demographic and clinical characteristics, treatment protocols and TE incidence. A systematic review was conducted to identify the rates of TE. The search strategy included text terms and MeSH headings for TP, rectal cancer and nT.

Results: Twelve of 86 studies met quality criteria for reporting TE complications and described 10 pulmonary emboli and three deep-vein thromboses in 3375 patients (overall TE rate = 0.38%). Ninety per cent of pulmonary emboli reported were fatal, suggesting significant under-reporting of TE events, even in high-quality studies.

Conclusion: The risk of fatal pulmonary embolism in studies examining nT in rectal cancer that reported complications systematically was one in 375 (0.27%; 95% CI: 0.09-0.44%). The overall TE rate, as well as the effectiveness of TP during nT, remains unknown. TE events should be systematically reported using common terminology frameworks in cancer studies.

Keywords: Rectal neoplasm; chemoradiotherapy; neoadjuvant therapy; thromboembolism.