K. Holli et al., PROGNOSTIC EFFECT OF TIMING OF OPERATION IN RELATION TO MENSTRUAL PHASE OF BREAST-CANCER PATIENT - FACT OR FALLACY, British Journal of Cancer, 71(1), 1995, pp. 124-127
The effects of the timing of operation in relation to menstrual phase
and hormone receptor protein positivity and concentration of the 5 yea
r survival of 267 premenopausal women with operable breast cancer were
evaluated. The patients were treated in the Tampere University Hospit
al Area in 1980-87, and information about menstrual cycle was recorded
before the operation. Patients operated on during the luteal phase (d
ays 15-32) had a trend towards a better survival rate (80.4%) than tho
se treated in the follicular phase (days 1-14) (75.9%), but the differ
ence did not reach statistical significance (P = 0.079). There was a s
mall difference in the positivity and concentration of hormone recepto
r proteins, depending on the phase of the menstrual cycle. A more sens
itive analysis found a statistically significant linear association be
tween survival and day since last menstrual period (LMP) which was not
totally accounted for by the variation in hormone receptor levels dur
ing the menstrual cycle or other main prognostic factors (P = 0.018 by
Cox's multivariate regression analysis when LMP was used as a continu
ous variable). One possible mechanism for the effect of timing can be
that physiological changes related to different phases of menstrual cy
cle unfavourably affect the quality of diagnostic and/or treatment pro
cedures. Variation in the lag between the diagnostic confirmation and
the operation of the patient affects the evaluation of such an effect
and may account for the inconsistent results reported so far.