Background. There is increasing evidence suggesting that genes located on the short arm of chromosome 11 play an important role in the development of human ovarian cancer. Recent cytogenetic and molecular studies have demonstrated the loss of genetic material in this region. Loss of normal growth regulatory genes may allow for the expression of tumorigenicity or lead to tumor progression.
Methods. The authors used DNA recombinant techniques to examine the frequency of allelic losses at four loci spanning the chromosomal region 11~15.1-11~15.5 in 40 patients with malignant ovarian tumors. DNA extracts from normal leukocytes and 48 tumor samples were analyzed by Southern blotting using the polymorphic probes pEJ6.6 (HRASZ), phins310 (INS), p20.36 (PTH), and pEM36 (CALCA).
Results. Reduction to homozygosity in the tumor DNA was found in 47.5'/0 of the informative cases (19 of 40). Comparing the results with clinical parameters, none of the well-differentiated tumors (6 of 40, Grade 1) and only one of the early stage tumors (6 of 40, International Federation of Gynecology and Obstetrics [FIGO] Stage I or 11) showed alterations in this chromosome region. Statistical analysis revealed a strong correlation of rate of loss of constitutional heterozygosity (LOH) and grade of differentiation, in the sense of higher 1 l p allele losses occurring in poorly differentiated tumors.
Conclusions. The authors concluded that the relatively high incidence of 1 l p allele losses marks an impor-