Aspirin was found to be associated with risk reduction of
secondary primary cancer for patients with head and neck squamous cell cancer (HNSCC). A population-based analysis of 18,243 patients
by Dr Yu-Shan Lin and colleagues from Taipei Medical University
Hospital, Taipei, Taiwan; found that aspirin use was associated with 25%
reduction in secondary primary cancer incidence of squamous cell carcinoma in
head and neck cancer patients. This was attributed mainly to reduced risk of
esophageal and stomach cancer.
The function of cyclooxygenase-2 (COX-2) inhibition has been
recognized as major mechanism of chemoprevention for aspirin. Many growth
factors and inflammatory cytokine known to promote cancer progression were
produced, packaged and secreted by thrombocytes, such as platelet derived
growth factor, vascular endothelial growth factor and transforming growth
factor-β . The inhibition of COX-2 enzymes in thrombocytes results in blockade
of synthesis of prostaglandins from
arachidonic acid.The downstream actions of PGE related with GF and cytokines
plays essential roles in angiogenesis, cell proliferation and invasion. A
platelet count of more than 400,000/μL was associated with higher mortality for
patient with HNSCC and the poor prognosis could be overcome by antiplatelet
medications.
Metformin (a sugar lowering agent) is a widely used for the
treatment of type 2 diabetes mellitus. Metformin use in diabetic patients has
been associated with decreased cancer incidence and mortality. This effect
seems to result from a reduction in circulating insulin levels, but there are
also data indicating direct anti-tumor effects of metformin.
Several studies demonstrated that metformin is important in
the inhibition of cell proliferation, G0/G1 cell cycle arrest, apoptosis and
regulation of various proteins involved in cancer pathways, thus corroborating
its potential in vitro and in vivo anti-tumor effects.
Three studies demonstrated that diabetics taking metformin
had decreased rates of local and regional recurrence and metastasis and
improved overall survival and disease-free survival rates. Individuals taking
metformin had a lower incidence of HNSCC than those not taking metformin.
Future studies are warranted to explore the use of aspirin and
metformin in in the management of HNSCC patients.
