Gender as a Prognostic Factor in CLL. Biological Pointers to the Improved Outcome of Women.

Gender is not widely regarded as a prognostic indicator in CLL. However, the combined data from three MRC randomised trials, CLL1, 2 and 3, and two observational studies for patients with Binet stage A, CLL2A and 3A, over a period of 20 years (1978-1998) totalling 2370 patients, showed a significant survival advantage for women (2p<0.0001). Cox regression analysis of the three randomised trials showed that gender, age, stage and response to therapy were independent prognostic variables. The response to treatment for women was also better than for men receiving the same therapies. The LRF CLL4 randomised trial, which started in 1999 shows the same trend. Preliminary results in 444 patients Binet stages A progressive, B and C showed the same CR/Nod.PR for both sexes (43.5%) but a higher PR rate in women (45%) vs men (36.5%) and a lower proportion of women non-responders to first line therapy (11.5% vs 20%). A number of laboratory investigations in CLL4, which included FISH analysis with five probes, VH mutational status, CD38 and ZAP-70 expression by flow cytometry, showed differences between the sexes, which were significant for 17p and 11q deletions combined and CD38, always in favour of women, as shown in Tables 1 and 2.

The clinical and laboratory results suggest that CLL is biologically more benign in women. Women have a lower incidence of CLL, an overall higher incidence of stage A (41.7%) than men (27.3%) in CLL 1, 2, 2A, 3 and 3A and respond better to treatment in all the trials. These differences may be underlined by a higher proportion of 13q del as sole abnormality, a lower proportion of 17p (p53 locus) and 11q deletions and lower levels of CD38. Data on VH mutations and ZAP-70 point in the same direction but the number of cases studied is still small. An additional factor that may play a role in the better outcome for women relates to the effect of oestrogen derivatives which are known to target selectively superoxide dismutase and induce cell kill (

Table 1: FISH analysis by gender (Dohner hierarchical model)

Table 2: Other biological markers