Effect of chronic administration of a gonadotropin-releasing agonist on luteal function and pregnancy rates in dairy cattle.

Increased embryonic losses may be associated with inadequate progesterone (P4) concentrations in high-producing lactating dairy cattle. The objectives of the present studies were to determine if chronic administration of a gonadotropin-releasing hormone (GnRH) agonist, Deslorelin, would increase circulating P4 concentrations and subsequently increase pregnancy rates in dairy cattle. Administration of Deslorelin for 12 days increased (p < .05) luteal volume and circulating P4 concentrations in primiparous lactating dairy cows, but increased only luteal volumes in multiparous cows. Treatment with Deslorelin increased Day 45 pregnancy rates in cows as compared to untreated controls. Chronic treatment with Deslorelin in dairy cattle; (a) increased luteal volume of the primary CL, (b) induced accessory CL, (c) increased circulating P4 concentration in primiparous cows only, (d) did not lengthen the estrous cycle upon removal of treatment, and (e) increased pregnancy rates. Although luteal volume was increased in multiparous cows and circulating P4 concentrations were not with Deslorelin treatment, there was an apparent effect on pregnancy rates. This hormonal strategy may represent a suitable model to address local effects of P4 and GnRH/luteinizing hormone on uterine environment and subsequent embryonic survival.

Differences in breast cancer incidence in Australia and England by age, extent of disease and deprivation status: women diagnosed 1980-2002.

OBJECTIVE: To compare breast cancer incidence in England and Australia by age, extent of disease and deprivation. METHODS: We analysed data for women aged 15-99 years diagnosed with breast cancer in England or Australia during the period 1990 to 1994, and in West Midlands or New South Wales during the period 1980 to 2002. We calculated three-year rolling average incidence rates and incidence rate ratios (IRR) between West Midlands and New South Wales by age, extent of disease and category of deprivation. RESULTS: Breast cancer incidence was higher in England than in Australia, and in West Midlands than in New South Wales but became more similar over time. Socio-economic differences in incidence were greater in New South Wales than in West Midlands. The most deprived women in West Midlands were diagnosed at a later stage of disease than the most deprived women in New South Wales. Incidence among elderly women was higher in West Midlands than in New South Wales. There were also high proportions of tumours with unknown stage among elderly women in West Midlands. CONCLUSIONS: Although the overall incidence of breast cancer is similar, differences by age, extent of disease and deprivation exist. IMPLICATIONS: The underlying reasons for these patterns require further examination.

Large differences in patterns of breast cancer survival between Australia and England: a comparative study using cancer registry data.

Survival from breast cancer in the UK is lower than in other countries in Western Europe, the USA and Australia. However, these international differences have not yet been examined in relation to tumor characteristics, treatment, screening history or other prognostic factors. We calculated relative survival by age, period of diagnosis, category of unemployment and extent of disease for women diagnosed with breast cancer during the period 1980-2002 in New South Wales (Australia) and West Midlands (England). National cancer registry data for each country for the period 1990-1994 were also examined. The excess hazard ratio was modeled as a function of prognostic covariables. Survival in Australia and New South Wales was higher than in England and West Midlands, respectively. In both regions, survival was lower for more deprived women and for the elderly. These differences were greater in West Midlands. Survival from localized and regional disease in New South Wales was higher than in West Midlands, but survival from metastatic disease was similar. Differences in breast cancer survival are unlikely to be entirely due to differences in data quality or to limitations of the analyses, although the measure of extent of disease used may not have been adequate to elucidate the effect of stage fully. One possible causal explanation is that the management of breast cancer differs between these regions. Further research should acquire better data on stage and investigate the effect of comorbidity and of patterns of care upon the difference in breast cancer survival between England and Australia.

Effect of a chemical manufacturing plant on community cancer rates.

BACKGROUND: We conducted a retrospective study to determine if potential past exposure to dioxin had resulted in increased incidence of cancer in people living near a former manufacturing plant in New South Wales, Australia. During operation, from 1928 to 1970, by-products of the manufacturing process, including dioxin and other chemical waste, were dumped into wetlands and mangroves, discharged into a nearby bay and used to reclaim land along the foreshore, leaving a legacy of significant dioxin contamination. METHODS: We selected 20 Census Collector Districts within 1.5 kilometres of the former manufacturing plant as the study area. We obtained data on all cases of cancer and deaths from cancer in New South Wales from 1972 to 2001. We also compared rates for some cancer types that have been associated with dioxin exposure. Based on a person's residential address at time of cancer diagnosis, or at time of death due to cancer, various geo-coding software and processes were used to determine which collector district the case or death should be attributed to. Age and sex specific population data were used to calculate standardised incidence ratios and standardised mortality ratios, to compare the study area to two comparison areas, using indirect standardisation. RESULTS: During the 30-year study period 1,106 cases of cancer and 524 deaths due to cancer were identified in the study area. This corresponds to an age-sex standardised rate of 3.2 cases per 1,000 person-years exposed and 1.6 deaths per 1,000 person-years exposed. The study area had a lower rate of cancer and deaths from cancer than the comparison areas. The case incidence and mortality due to lung and bronchus carcinomas and haematopoietic cancers did not differ significantly from the comparison areas for the study period. There was no obvious geographical trend in ratios when comparing individual collector districts to New South Wales according to distance from the potential source of dioxin exposure. CONCLUSION: This investigation found no evidence that dioxin contamination from this site resulted in increased cancer rates in the potentially exposed population living around the former manufacturing plant.