Cavity Shave of Margins in Breast Cancer

Chagpar et al report on their article in NEJM the results of a 235 patients trial with breast cancer stage 0 to III who were undergoing partial mastectomy, with or without resection of selective margins, and further cavity shave margins resected.

The median age of the patients was 61 years (range, 33 to 94). On pathological testing, 54 patients (23%) had invasive cancer, 45 (19%) had ductal carcinoma in situ, and 125 (53%) had both; 11 patients had no further disease. The median size of the tumor in the greatest diameter was 1.1 cm (range, 0 to 6.5) in patients with invasive carcinoma and 1.0 cm (range, 0 to 9.3) in patients with ductal carcinoma in situ.  The rate of positive margins after partial mastectomy (before randomization) was similar in the shave group and the no-shave group (36% and 34%, respectively; P=0.69). After randomization, patients in the shave group had a significantly lower rate of positive margins than did those in the no-shave group (19% vs. 34%, P=0.01), as well as a lower rate of second surgery for margin clearance (10% vs. 21%, P=0.02).

The authors concluded that cavity shaving halved the rates of positive margins among patients with partial mastectomy.

N Engl J Med 2015; 373:503-510

Screening mammography has not saved lives

Harding, et al in their article published in JAMA Intern Med report on associations between screening mammography and the incidence and mortality from breast cancer, as well as tumor size.

A study of 16 million women 40 years or older who resided in 547 US counties reporting to the Surveillance, Epidemiology, and End Results cancer registries during the year 2000. Of these women, 53 207 were diagnosed with breast cancer that year and were followed up for the next 10 years.

Across the US counties, there was a positive correlation between the extent of screening and breast cancer incidence but not with breast cancer mortality. An absolute increase of 10 percentage points in the extent of screening was accompanied by 16% more breast cancer diagnoses but no significant change in breast cancer deaths. In an analysis stratified by tumor size, they found that more screening was strongly associated with an increased incidence of small breast cancers (≤2 cm) but not with a decreased incidence of larger breast cancers (>2 cm). An increase of 10 percentage points in screening was associated with a 25% increase in the incidence of small breast cancers and a 7% increase in the incidence of larger breast cancers.

They found that screening mammography results in the diagnosis of additional small cancers but no concomitant decline in the detection of larger cancers, which might explain the absence of any significant difference in the overall rate of death from the disease. Together, these findings suggest widespread overdiagnosis.

Significant Number Of Misses and Mistakes May Occur When Radiologists Increase Reporting Speeds.

A study published by Sokolovskaya et al in the Journal of the American College of Radiology a significant amount of misses and major reporting errors occur when radiologists increase imaging reporting speeds.

The authors selected a sample set of 53 abdominal-pelviic CT scans of variable complexity that were performed at a teaching hospital. They classified the CT scans into 4 categories based on their level of complexity, with level 4 representing the most-complex cases. Five attending radiologists participated in the study. Radiologists were randomly assigned a set of 12 studies, of varying complexity, to dictate at their normal speed, and a separate set of 12 studies, of similar complexity, to read at a speed that was twice as fast as their normal speed.

Reading at the faster speed resulted in more misses for 4 of the 5 radiologists. The total number of major misses for the 5 radiologists, when they reported at the faster speed, was 16 of 60 reported cases, versus 6 of 60 reported cases at normal speed; P = .032. The average interpretation error rate of major misses among the 5 radiologists reporting at the faster speed was 26.6%, compared with 10% at normal speed.

The authors report a significant positive correlation between faster reading speed and the number of major misses and interpretation errors.

J Am Coll Radiol. 2015 Jul;12(7):683-8