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Breast cancer is the most common form of malignancy in Scottish women and its incidence appears to be increasing with time. It is therefore important to identify factors associated with risk and outcome. In this thesis two separate but interrelated social aspects of the natural history of breast cancer have been examined - (i) the location of the primary tumour within the breast in two groups of patients diagnosed 40 years apart and (ii) the effects of socioeconomic status on prognostic factors and outcome of patients with breast cancer. Whilst breast cancer occurs equally in right and left breasts, tumours most commonly affect the upper outer quadrant (UOQ) of the breast. However, there is no information as to whether the incidence has changed over time. To address this, the present study investigated two groups of women diagnosed with breast cancer in the south-east of Scotland between either 1957-1959 or 1997-1999 (ie 40years apart). The earlier group represent 1158 of 1207 women referred to radiation oncologists in the region and the later group comprised 1477 of about 1600 women referred to the Edinburgh Breast Unit. Whilst the age, menopausal status and laterality of the patients were similar in both groups, the tumour size and tumour location within the breast were significantly different in the two groups. Thus, there was significant reduction in T stage with year of diagnosis (p < 0.0001), the incidence of Tl, T2, and T3/4 being 15.6%, 51.9% and 25.6% in the earlier cohort compared with 49.3%, 36.8% and 13.7% in the later group. The overall distribution within the breast was significantly different by chi-squared analysis (p < 0.0001). In terms of individual quadrants 469 of 1158 (40.5%) tumours were located in the upper outer quadrant (UOQ), whereas in the more recent cohort it was 788 of 1477 (53.4%), this increase in proportion being statistically significant (p < 0.0001). Occurrence in the lower outer quadrant (LOQ) also significantly increased (p < 0.028) but was significantly reduced in the upper inner quadrant (UIQ) and centrally (both p < 0.0001). Analysing data on location for each T stage separately showed that the increased incidence in the UOQ with time was apparent for each subgroup. The increased incidence in UOQ tumours over time is therefore not a simple reflection of decreased size between the two time groups. The underlying reason(s) for this change in distribution with time requires further study. Affluent women have a higher incidence of breast cancer than socially deprived women but may have a better outcome from the disease. The aims of the study in this thesis were to (i) quantify and investigate differences in survival and recurrence from breast cancer between women differing in socioeconomic status from the south-east of Scotland and (ii) define the contribution of underlying factors to this variation. To do this, 502 patients with non-metastatic invasive breast cancer referred to the Edinburgh Breast Unit between 1985 and 1993 were stratified according to Carstairs Index. This subdivides individuals into deprivation categories (DEPCAT) according to postal address. The most affluent have DEPCAT 1 and 2 and the most deprived areas are DEPCAT 6 and 7. The majority of women fell into DETCAT status 3 and 4 (25.1 and 27.1 respectively) whilst 10.4 and 16.3 % were placed in the most affluent DEPCAT 1 and 2 groups and 15.1, 2.6 and 3.4% in the most deprived DEPCAT 5, 6 and 7 groups respectively. To increase numbers in small groups and have approximately equal numbers, analyses were also performed combining DEPCAT scoresl and 2 to provide Zone A and DEPCAT scores 5,6 and 7 to provide Zone D (DEPCAT 3 was zone B and DEPCAT 4 was zone C). In terms of recurrence, there were trends for more affluent DEPCAT categories to have a better outcome but these did not reach statistical significance. However women from the most affluent zone had significantly better DFI than the socially deprived (p= 0.0 by Kaplan Meier).More affluent women (on the basis of either DEPCAT groups or zones) had a better survival compared to the most deprived. Based on single follow up time of 5 years, survival difference were statistically significant by chi-square analysis (p=0.026 for DEPCAT and 0.011 for zones). Furthermore, using the total follow-up until 2002, Kaplan Meier analysis of SES zones showed that affluent women had a significantly better survival (p=0.02). SES was not related to menopausal status or established prognostic factors such as lymph node status, tumour size and ER status, although lymph node status and tumour size were highly significantly associated with patient survival (p < 0.0001 and 0.0006 respectively by Kaplan Meier). Given that these established factors do not relate to SES and that the patients were treated by defined protocols irrespective of SES, the factors underlying the differences in outcome between affluent and deprived women in Edinburgh remain undefined. Further research is required to identify other reasons for poorer outcomes in deprived women, with a view to reducing these survival differences. These 2 studies provide further evidence for social factors influence the natural history of breast cancer. |
