Occult axillary lymph node metastases in "node-negative" breast carcinoma.

The presence of occult axillary nodal metastases was evaluated in 159 patients with "node-negative" invasive breast carcinoma. Multiple additional levels of the lymph nodes were examined with hematoxylin-eosin staining and keratin immunostaining. Occult nodal metastases were detected in 50 (31%) patients; of these, 28 (17%) were detectable by hematoxylin-eosin stain alone, while the other 22 (14%) consisted of mostly single cells or very small clusters and required immunostaining for detection. The size of the metastatic deposit was < or = 0.2 mn in 31 (19%) patients and greater than 0.2 mm in 19 (12%) patients. Occult nodal metastasis correlated with the presence of peritumoral lymphatic invasion (P = .02) and was seen more frequently with larger tumor size, increased microvasculature, and aneuploidy. As a group occult metastases had no significant prognostic impact. However, patients with metastases measuring greater than 0.2 mm had significantly worse recurrence (P = .02), disease-free survival (P = .04), and overall survival (P = .07) rates; those with metastases detectable by hematoxylin-eosin stain alone also had a less favorable, although not significant, outcome. In contrast, patients with occult metastases that were < or = 0.2 mm or that were detected only by immunostaining had a survival rate comparable to and in fact slightly higher than that of the group without occult metastasis; 23 of these patients were without recurrence after a median follow-up of 11 years. Extension into perinodal soft tissue was an unfavorable feature. In a multivariate analysis peritumoral lymphovascular invasion and increased microvasculature were the most important prognostic parameters, and the presence of occult metastases greater than 0.2 mm was no longer significant. Our data suggest that occult metastases < or = 0.2 mm, especially those consisting of single cells, do not add useful prognostic information, and immunohistochemical studies to detect them are probably unnecessary. Larger metastases and extranodal involvement may have important prognostic value, but in this study they accounted for only 20% of patients who had recurrences or 6% of the total population. This underscores the importance of using more than one prognostic parameter in evaluating breast carcinoma.

Different Roles for Phytochrome in Etiolated and Green Plants Deduced from Characterization of Arabidopsis thaliana Mutants.

We have isolated a new complementation group of Arabidopsis thaliana long hypocotyl mutant (hy6) and have characterized a variety of light-regulated phenomena in hy6 and other previously isolated A. thaliana hy mutants. Among six complementation groups that define the HY phenotype in A. thaliana, three (hy1, hy2, and hy6) had significantly lowered levels of photoreversibly detectable phytochrome, although near wild-type levels of the phytochrome apoprotein were present in all three mutants. When photoregulation of chlorophyll a/b binding protein (cab) gene expression was examined, results obtained depended dramatically on the light regime employed. Using the red/far-red photoreversibility assay on etiolated plants, the accumulation of cab mRNAs was considerably less in the phytochrome-deficient mutants than in wild-type A. thaliana seedlings. When grown in high-fluence rate white light, however, the mutants accumulated wild-type levels of cab mRNAs and other mRNAs thought to be regulated by phytochrome. An examination of the light-grown phenotypes of the phytochrome-deficient mutants, using biochemical, molecular, and morphological techniques, revealed that the mutants displayed incomplete chloroplast and leaf development under conditions where wild-type chloroplasts developed normally. Thus, although phytochrome may play a role in gene expression in etiolated plants, a primary role for phytochrome in green plants is likely to be in modulating the amount of chloroplast development, rather than triggering the initiation of events (e.g., gene expression) associated with chloroplast development.