BOTH CLASS-I AND CLASS-II HLA ANTIGENS ARE THYROID-CANCER SUSCEPTIBILITY FACTORS

It has been established that HLA antigens are susceptibility factors f or different cancers, including thyroid tumors. However, the diversity and sometimes weak and contradictory associations found have frequent ly led to the view that the HLA and tumorigenesis links might be the r esult of statistical errors. However. it has recently been established that it is indeed a currently complex and unexplained but real phenom enon. which may be crucial in preventing several types of cancer. In t he present work we have found in a relatively large series of thyroid cancer patients (n=161) that both HLA class I (B35) and class II (DR11 ) antigens are susceptibility factors only in the papillary tumor grou p of patients, B35 association p value is found at the limit of signif icance (p(c(120))=0.05); the follicular group did not show any HLA ass ociation, suggesting that the etiopathogenesis of each type of cancer is different. HLA-B35 and DR11 are not working together to induce tumo rigenesis and each of them seems to confer susceptibility by using dif ferent pathways or by being markers of distinct neighboring susceptibi lity genes. DR4 has also been found in 86% (n=6) of Hurthle cell carci noma. No association has been found between HLA and disease activity. HLA mechanisms of association to cancer are discussed and a world-wide HLA/tumorigenic study is proposed to obtain a clear picture of the pu zzling and controversial susceptibility markers found in different tum ors and in different ethnic groups.