The levels cytosol estrogen (ERc) and progesterone (PRc) receptors wer
e determined in 315 primary breast cancers of female Arab patients age
d 23-80 years. Most of breast cancers (78%) occurred in women aged 21-
50 years, and only 22% were in women aged 51-80 years. Breast cancers
containing ERc and PRc concentrations in the range 5-50 fmol/mg of cyt
osol protein (mg c.p.) were found with similar frequency in women aged
under or over 50 years (53% for ERc and 43% for PRc, respectively). O
n the other hand, breast cancers with ERc values of > 50 and > 100 fmo
l/mg cp. were twice as frequent in women aged over 50 years as in wome
n aged under 50 years. The frequency of breast cancers with PRc level
of over 50 fmol/mg c.p. in women aged over 50 years was only half that
in those aged under 50 years. In breast cancers of Kuwait Arab women
the higher values of ERc (> 100 fmol/mg cp.) and PRc (> 50 fmol/mg c.p
.) were less frequent than in other populations reported in literature
. The low frequency of breast cancer in postmenopausal Kuwait women is
associated with low proportions of tumors with higher ERc and PRc con
tents. In contrast to this, data from literature indicate that in the
North Western European and American populations the postmenopausal inc
idence rise or breast cancers is associated with increased proportions
of tumors with higher ERc and PRc levels.