The role of axillary dissection in mammographically detected carcinoma.

BACKGROUND: Axillary dissection remains a standard component of the treatment of invasive carcinoma of the breast. The presence of metastases to the regional lymph nodes guides adjuvant therapy and aids in determining prognosis. Mammography results in the discovery of small and often node-negative carcinomas of the breast. STUDY DESIGN: This 15-year, retrospective analysis investigated whether certain patients with small tumors could be spared the morbidity of axillary dissection. RESULTS: Medical records showed that from January 1980 to May 1995, 4,543 needle localization biopsies were done at York Hospital because of abnormalities detected on mammograms. Of these, 703 (15.5 percent) proved to be carcinoma. Of the carcinomas, 68 percent were infiltrating ductal carcinoma, 26 percent were ductal carcinoma in situ, and 5.4 percent were infiltrating lobular carcinoma. Axillary dissection was done on 588 patients, and 88.1 percent of the patients had no metastases to axillary lymph nodes. No axillary metastases were present in 109 patients with ductal carcinoma in situ who underwent axillary lymph node dissection or in 21 patients with microscopic invasive tumors. Only two of 54 patients with a T1a tumor (tumor [T], < or = 0.5 cm) had positive axillary nodes. Only one of 29 patients with a well-differentiated T1b tumor (T, > 0.5 to < or = 1 cm) had metastatic axillary nodes. In the presence of negative axillary lymph nodes, 19.2 percent of patients with a T1a tumor, 33.7 percent of patients with a T1b tumor, 60 percent of patients with a T1c tumor (T, > 1 to < or = 2 cm), and 78.9 percent of patients with a T2 tumor (T, > 2 cm) were given adjuvant chemotherapy or hormonal therapy. CONCLUSIONS: Patients with ductal carcinoma in situ and microscopic invasive tumors do not require node dissections. Possibly patients with T1a tumors and patients with well-differentiated, estrogen-receptor positive, progesterone-receptor positive, T1b tumors can also be spared axillary node dissection. By following this approach on occasion, patients with positive nodes might not undergo axillary lymph node dissection, but they may still be offered adjuvant therapy.

A method to predict the percutaneous permeability of various compounds: shed snake skin as a model membrane.

Penetration of various compounds through shed snake skin was measured in vitro to examine the effect of lipophilicity and molecular size of a compound on permeability through this model membrane. The permeabilities were found to be controlled by the lipophilicity and the molecular size of the permeant. The smaller and the more lipophilic the compound, the greater the permeability. Equations have been developed to predict the permeability from the molecular weight and the distribution coefficient of a compound. Further, the lipophilicity of shed snake skin is similar to that of human skin and the response of shed snake skin to the molecular size of a permeant is more similar to human skin than to hairless mouse skin. Considering the similarities between shed snake skin and human stratum corneum in terms of structure, composition, and permeability characteristics, the same considerations may apply to permeability through human stratum corneum.

Sites of cerebrovascular injury induced by radiographic contrast media.

The object of this study was to determine the type of cerebral vessel affected by injection of radiopaque contrast agents used in cerebral angiography. Seventeen rabbits were prepared surgically for a left intracarotid injection of methylglucamine iothalamate (Conray 60) or methylglucamine diatrizoate (Reno-M-60). Extravasations of the tracers, Evans blue and horseradish peroxidase, occurred in the left half of the brain and occasionally in the right half. Within those areas of blood-brain barrier breakdown, the frequency of leakage was 60% for arterioles, 25% for venules, and 12% for capillaries. The leakage appeared to be primarily intercellular, rather than intracellular. This study provides evidence that greater blood-brain barrier alterations occur in arterioles and venules than in capillaries following cerebral angiography.

Effect of electrical stimulation of the hippocampus upon corticosteroid levels in the freely-behaving, non-stressed rat.

The influence of the hippocampus upon pituitary release of adrenocorticotropic hormone (ACTH) was studied in male Sprague-Dawley rats which had concentric bipolar stainless stell electrodes chemically implanted in the dorsal and ventral hippocampus. Blood samples were withdrawn at half-hour intervals from a cannula in the right atrium. Plasma corticosterone levels reflected ACTH release. 30 min of 25 or 250-cps electrical stimulation of the hippocampus in the freely-behaving, non-stressed rat resulted in significant increases in basal plasma corticosterone levels evident at the end of stimulation. In afternoon experiments, after stimulation at either hippocampal site with 25 cps only, the increase was followed by a delayed inhibitroy phase and temporary inhibition of the circadian rise in corticosterone levels. The inhibitory effect was more pronounced with ventral than with dorsal hippocampal stimulation. The basis for these differential effects is discussed in terms of the anatomical organization of the hippocampus.