Histologic specificity of the effect of age at birth of first child on breast cancer risk

Established breast cancer risk factors by clinically important tumour characteristics

Breast cancer is a morphologically and clinically heterogeneous disease; however, it is less clear how risk factors relate to tumour features. We evaluated risk factors by tumour characteristics (histopathologic type, grade, size, and nodal status) in a population-based case-control of 2386 breast cancers and 2502 controls in Poland. Use of a novel extension of the polytomous logistic regression permitted simultaneous modelling of multiple tumour characteristics. Late age at first full-term birth was associated with increased risk of large (> 2 cm) tumours (odds ratios (95% confidence intervals) 1.19 (1.07-1.33) for a 5-year increase in age), but not smaller tumours (P for heterogeneity adjusting for other tumour features (Phet) = 0.007). On the other hand, multiparity was associated with reduced risk for small tumours (0.76 (0.68-0.86) per additional birth; Phet = 0.004). Consideration of all tumour characteristics simultaneously revealed that current or recent use of combined hormone replacement therapy was associated with risk of small (2.29 (1.66-3.15)) and grade 1 (3.36 (2.22-5.08)) tumours (Phet = 0.05 for size and 0.0008 for grade 1 vs 3), rather than specific histopathologic types (Phet = 0.63 for ductal vs lobular). Finally, elevated body mass index was associated with larger tumour size among both pre- and postmenopausal women (Phet = 0.05 and 0.0001, respectively). None of these relationships were explained by hormone receptor status of the tumours. In conclusion, these data support distinctive risk factor relationships by tumour characteristics of prognostic relevance. These findings might be useful in developing targeted prevention efforts.

Reproductive risk factors for breast cancer by receptor status, histology, laterality and location

It is well established that a woman's reproductive history influences her risk of breast cancer. We examined whether the effect of reproductive history was similar for different sub-types of breast cancer. The study was based on a population-based cohort of 1.5 million Danish women born between 1935 and 1978, with individual information on births. Between 1978 and 1994, 10,790 incident cases of breast cancer were identified in a nationwide cancer registry, including detailed information on receptor status, histology, laterality and location of the tumour. Overall, the incidence of breast cancer was 13% lower in parous compared with nulliparous women. This reduction was significantly stronger for mucinous than for ductal carcinomas and for tumours located centrally than for those non-central in the breast. Overall, the incidence in parous women increased by 10% by each 5-year postponement of their first birth. For the incidence of lobular carcinomas this increase was significantly stronger, and for mucinous carcinomas it tended to be stronger than for ductal carcinomas. For the incidence of centrally located tumours the increase was stronger than for non-centrally located tumours. On average, there was a 10% decrease in breast-cancer risk by each additional birth. This decrease was seen in most sub-types, but not for lobular carcinomas of for centrally located tumours. According to our findings, lobular and mucinous carcinomas and centrally located tumours may have risk-factor profiles that differ from other types of breast cancer.

Histologic types of breast carcinoma in relation to international variation and breast cancer risk factors. WHO Collaborative Study of Neoplasia and Steroid Contraceptives

Associations between breast cancer risk factors and histologic types of invasive breast carcinoma were studied in 2,728 patients. Lobular and tubular carcinomas occurred with increased relative frequency in most high-risk groups. The proportion of these types increased with age to a maximum at 45-49 years and decreased in the following decade. Significantly increased proportions of lobular and tubular carcinomas were also associated with high-risk countries, prior benign breast biopsy, bilateral breast cancer, concurrent mammary dysplasia, high age at first live birth, never-pregnant patients compared to those with a first live birth before age 20, private pay status, and length of education. Nonsignificant increases were associated with family history of breast cancer, less than 5 live births, less than 25 months total of breast feeding, use of oral contraceptives or IUD, and high occupational class. As a general trend, the higher the overall relative risk, the higher the proportion of lobular and tubular carcinomas. The occurrence of other histologic types also increased with increased breast cancer risk, but to a smaller degree than for lobular/tubular carcinomas. It is suggested that all hormonally related, socio-economic and geographic risk factors exert their effect by selectively increasing number of lobular cells at risk. Family history of breast carcinoma and age over 49 years did not follow the general trend parallel increases in the proportion of lobular/tubular carcinomas and breast cancer risk, and may operate through other mechanisms.

Effect of age at first childbirth on risk of developing specific histologic subtype of breast cancer

Epidemiologic variables related to breast cancer risk were assessed in a case-control study of 332 women with breast carcinoma and 1353 comparison women. Risk factors for breast cancer as a whole included nulliparity, late age at first childbirth, early age at menarche, late age at menopause, personal history of benign breast disease, family history of breast cancer, and among postmenopausal women, body weight. These risk factors were then analyzed with respect to histologic subtype of breast cancer involved, i.e., duct-derived or lobular tumors, to determine whether the association between any of the risk factors and breast cancer varied according to histopathologic subtype. Histologic subtype for the 316 cases reviewed included 284 duct cancers and 32 lobular carcinomas. Although slight differences were noted among some of the risk factors and the variety of cancer, none of the differences was marked except for the variable age at birth birth. For ductal carcinoma, the risk was highest among nulliparous women and decreased the younger a woman was at the time she gave birth to her first child. The risk of infiltrating lobular carcinoma, however, was lowest among nulliparous females or those who had given birth at a young age and increased the older a woman was when she gave birth to her first child.

Epidemiology of breast carcinoma IV: age and histologic tumor type

The purpose of this study was to correlate major chronologic events known to have a bearing on the risk for developing breast carcinoma with histologic tumor type. Data were obtained for 1024 consecutively treated patients with the seven most common forms of mammary carcinoma. The age of occurrence of the following events was determined: menarche; first marriage; first pregnancy and first childbirth; last pregnancy and last childhood; diagnosis. The interval between each of these events and diagnosis of breast cancer was also calculated. Patients with medullary carcinoma had a significantly lower mean age at diagnosis than those with any of the other tumor types. Because of the lower mean age at diagnosis, medullary carcinoma patients were found to have significantly shorter intervals between age at diagnosis and the following: menarche, first pregnancy or first childbirth, and last pregnancy or last childbirth. Intervals between age at diagnosis and these other events were not significantly different among patients with other types of carcinoma. The ages of menarche, marriage, or pregnancy were not related independently to any tumor type. These data indicate that except for current age, the age of occurrence of major risk factors for developing breast cancer is unrelated to the histological type of tumor a patient develops.