Axillary lymph node dose with tangential breast irradiation.

PURPOSE: The advent of sentinel lymph node mapping and biopsy in the staging of breast cancer has resulted in a significant decrease in the extent of axillary nodal surgery. As the extent of axillary surgery decreases, the radiation dose and distribution within the axilla becomes increasingly important for current therapy planning and future analysis of results. This analysis examined the radiation dose distribution delivered to the anatomically defined axillary level I and II lymph node volume and surgically placed axillary clips with conventional tangential breast fields and CT-based three-dimensional (3D) planning. METHODS AND MATERIALS: Fifty consecutive patients with early-stage breast cancer undergoing breast conservation therapy were evaluated. All patients underwent 3D CT-based planning with conventional breast tangential fields designed to encompass the entire breast parenchyma. Using CT-based 3D planning, the dose distribution of the standard tangential breast irradiation fields was examined in relationship to the axillary level I and II lymph node volumes. Axillary level I and II lymph node anatomic volumes were defined by CT and surgical clips placed during complete level I-II lymph node dissection. Axillary level I-II lymph node volume doses were examined on the basis of the prescribed breast radiation dose and 3D dose distribution. RESULTS: All defined breast volumes received > or =95% of the prescribed dose. By contrast, the 95% isodose line encompassed only an average of 55% (range, 23-87%) of the axillary level I-II lymph node anatomic volume. No patient had complete coverage of the axillary level I-II lymph node region by the 95% isodose line. The mean anatomic axillary level I-II volume was 146.3 cm(3) (range, 83.1-313.0 cm(3)). The mean anatomic axillary level I-II volume encompassed by the 95% isodose line was 84.9 cm(3) (range, 25.1-219.0 cm(3)). The mean 95% isodose coverage of the surgical clip volume was 80%, and the median value was 81% (range, 58-98%). The mean volume deficit between the axillary level I-II volume and the surgical clip volume was 41.7 cm(3) (median, 30.0 cc). CONCLUSION: In this study, standard tangential breast radiation fields failed to deliver a therapeutic dose adequately to the axillary level I-II lymph node anatomic volume. No patient received complete coverage of the axillary level I-II lymph node volume. Surgically placed axillary clips also failed to delineate the level I-II axilla adequately. Definitive irradiation of the level I and II axillary lymph node region requires significant modification of standard tangential fields, best accomplished with 3D treatment planning, with specific targeting of anatomically defined axillary lymph node volumes as described, in addition to the breast parenchymal volumes.

Risk of mortality by histologic type of breast cancer among women aged 50 to 79 years.

BACKGROUND: Recent studies suggest that the use of combined estrogen and progestin hormone replacement therapy is associated with an increased risk of invasive lobular carcinoma (ILC), but that it has little association with risk of invasive ductal carcinoma (IDC). Also, the incidence rates of ILC have risen over the past 10 years while those of IDC have remained constant. Differences in survival rates by histologic types of tumor have been reported, but few of the published studies were population based or had adequate power to address this issue. METHODS: We conducted a retrospective cohort study spanning the years 1974 through 1998 using data from the 9 cancer registries that have participated in the Surveillance, Epidemiology, and End Results Program since 1974. The cohort consisted of 164 958 women aged 50 to 79 years who had been diagnosed as having 1 of 7 histologic types of invasive breast cancer. Risks of mortality due to any cause were estimated using the Cox proportional hazards model. RESULTS: Women with ILC had a risk of mortality 11% lower than women with IDC. The magnitude of this difference has increased over the past 10 years and, from 1994 through 1998, the risk of mortality was 26% lower for women with ILC. Also, the risk of mortality was between 8% and 34% lower in women with mucinous carcinoma, comedocarcinoma, or medullary, tubular, and papillary carcinomas compared with women with IDC. CONCLUSIONS: Differences in prognosis by histologic type of breast cancer were identified. The survival rate of women 50 to 79 years old who have ILC, the cancer whose histologic type is the most closely linked with the use of combined estrogen and progestin hormone replacement therapy, is more favorable than that of women with IDC and appears to be improving over time.

Trends in incidence rates of invasive lobular and ductal breast carcinoma.

CONTEXT: Research has suggested that use of combined estrogen and progestin hormone replacement therapy (CHRT) increases breast cancer risk and that CHRT use is more strongly associated with the risk of invasive lobular breast carcinoma than that of invasive ductal carcinoma. Lobular carcinoma is less common than ductal carcinoma but can be more difficult to diagnose because of its subtle elusive infiltrative pattern. OBJECTIVE: To evaluate trends in invasive lobular and ductal carcinoma incidence rates from 1987 through 1999, during which time use of CHRT increased in the United States. DESIGN: Descriptive epidemiologic study. SETTING: Nine cancer registries that participate in the Surveillance, Epidemiology, and End Results (SEER) program of the National Cancer Institute and that cover Atlanta, Ga; Detroit, Mich; San Francisco-Oakland, Calif; Seattle, Wash; and Connecticut, Hawaii, Iowa, New Mexico, and Utah. POPULATION: Women 30 years of age and older residing in the areas covered by the 9 SEER registries. MAIN OUTCOME MEASURES: Proportional changes in incidence rates of invasive lobular and ductal carcinoma among women with no prior history of breast cancer. RESULTS: A total of 190 458 women were included in this analysis who were identified through the registries as having invasive breast cancer; 7682 of the 198 140 potentially eligible women (ie, those identified as not having in situ breast cancer) were excluded from this analysis because stage of cancer was unknown. Invasive breast cancer incidence rates adjusted for age and for SEER historic stage increased 1.04-fold (95% confidence interval [CI], 1.004-1.07) from 1987-1999 (206.7/100 000 to 214.1/100 000, age-adjusted). However, incidence rates of tumors classified as lobular increased 1.52-fold (95% CI, 1.42-1.63), and those classified as mixed ductal-lobular increased 1.96-fold (95% CI, 1.80-2.14); rates of these types combined increased 1.65-fold (95% CI, 1.55-1.78) (19.8/100 000 to 33.4/100 000, age-adjusted). In contrast, ductal carcinoma rates remained largely constant (153.8/100 000 to 155.3/100 000, age-adjusted; proportional change, 1.03 [95% CI, 0.99-1.06]). The proportion of breast cancers with a lobular component increased from 9.5% in 1987 to 15.6% in 1999. CONCLUSIONS: Ductal carcinoma incidence rates remained essentially constant from 1987-1999 while lobular carcinoma rates increased steadily. This increase presents a clinical challenge given that lobular carcinoma is more difficult to detect than ductal carcinoma by both physical examination and mammography.

Access to multidisciplinary cancer care: is it linked to the use of breast-conserving surgery with radiation for early-stage breast carcinoma?

BACKGROUND: Breast-conserving surgery (BCS) with radiation (BCSR) requires a multidisciplinary care approach between surgeons and radiation oncologists. METHODS: This retrospective cohort study examined the use of preoperative radiation oncology consultation and whether use of or distance to this care was associated with treatment choice among 1188 women age > or = 65 years who were diagnosed with local or regional breast carcinoma in Washington State in 1994 and 1995. Study outcomes included rates of BCSR; BCS alone; and mastectomy; and radiation therapy among women who underwent BCS. RESULTS: Only 29% of patients in the current study consulted with a radiation oncologist preoperatively, and less than half of the patients (46.6%) consulted with either a medical oncologist or a radiation oncologist. Among women who underwent either BCSR or mastectomy, the odds of undergoing BCSR among women who had a preoperative radiation oncology consultation were 6.7 times the odds of women who did not have the consultation (P < or = 0.001). Similarly, the odds of receiving radiation therapy among women who underwent BCS and had a preoperative radiation oncology consultation were 5 times the odds of women who did not have the consultation (P < 0.001). The 3.4% of women who lived > 50 miles from the radiation therapy center had the lowest BCSR rate (15.8%) and had the lowest radiation therapy rate among women who underwent BCS (54.5%), although these findings were not statistically significant in adjusted analyses. CONCLUSIONS: A preoperative visit with a radiation oncologist was associated strongly with BCSR use. More should be done to evaluate the role of multidisciplinary consultation in the decision to use BCSR.

Retinoids, retinoic acid receptors, and breast cancer.

Retinoids comprise both naturally and synthetically occurring compounds that have been proven to be differentiation agents for a variety of neoplasias, including breast cancer and promyelocytic leukemia in animal models and humans. They offer a unique panoply of therapeutics for the prevention or treatment of breast cancer. Nonetheless, considerable controversy remains as to the efficacy and potential toxic side-effects and as to which group of patients may most benefit. In this article, we review evidence of retinoid efficacy in breast cancer in humans and in animal models and provide possible mechanisms of retinoid action in breast cancer treatment, focusing on the roles of the different retinoic acid receptors and the metabolic pathways necessary for gene activation and cellular homeostasis.

Changing incidence of lobular carcinoma in situ of the breast.

Estimating the incidence of lobular carcinoma in situ (LCIS) of the breast is challenging because it lacks both clinical and mammographic signs and is usually an incidental finding in breast biopsies performed for other reasons. In general, population-based studies are believed to provide the most accurate measures, but few documenting changes in LCIS incidence rates over time have been reported. Age-adjusted age-specific LCIS incidence rates among women with no prior history of in situ or invasive breast carcinoma from 1978 to 1998 were obtained from nine population-based cancer registries that participate in the Surveillance, Epidemiology, and End Results (SEER) Program. Linear trends were evaluated using negative binomial regression. Overall, LCIS incidence rates increased fourfold (95% confidence interval, 2.9-5.6) over the study period. Specifically, they rose from 0.90/100,000 person-years in 1978-80 to 2.83/100,000 person-years in 1987-89, but then increased only modestly up to 1996-98 where the incidence rate was 3.19/100,000 person-years. However, among women 50-79 years of age, LCIS incidence rates increased continuously over the study's duration. In 1996-98, 50-59 year-olds had the highest incidence rate (11.47/100,000 person-years) and experienced the greatest absolute increase in incidence over the study period (9.48/100,000 person-years). LCIS incidence rates have steadily increased from 1978 to 1998 only among postmenopausal women. Further research is required to assess what factors are contributing to these trends.