Breast MRI Improves depiction of DCIS Components

A study by Kuhl et al published in Radiology found magnetic resonance imaging (MRI) of the breast improves depiction of ductal carcinoma in situ (DCIS) components of invasive breast cancers prior to surgery.

The authors performed a prospective two-center study of 593 patients with biopsy proven invasive breast cancer that underwent breast MRI in addition to conventional imaging. 

The outcomes showed surgical-pathologic evaluation demonstrated DCIS components in 139 (23%) women. MRI had significantly higher sensitivity in the diagnosis of DCIS components pre-operatively in (84%; 118 women out of 139) than that of conventional imaging, which detected (36%; 51 of the 139 women). More than 50 percent of DCIS components were detected with MRI alone. 

The researchers also found the sensitivity benefits of MR imaging over conventional imaging improved with increasing relative size, and with increasing nuclear grade of DCIS components. Positive margin rates were generally low and did not diverge significantly between the 139 women with DCIS components versus the 454 women who lacked them.

The authors concluded that breast MRI improves depiction of DCIS components of invasive breast cancers before surgery.

How effective is screening mammography?

A study by Welch et al published in New Engl J Med added to the growing evidence that for every woman who was helped by screening mammography many have been harmed.

The authors used data from the SEER program from 1975 through 2012. They calculated the size-specific cancer case fatality rate in women 40 year old and older for two time periods: a baseline period before the implementation of widespread screening mammography (1975 through 1979) and a period encompassing 10 years (2000 through 2002).

Screening did result in more cancers being detected, with invasive tumors measuring <2 cm or in situ carcinomas increased from 36% to 68%; and the detected tumors that were large, which were invasive cancers and measuring ≥2 cm decreased from 64% to 32%.  Surprisingly though the data suggest that only about 30 of the 162 additional small tumors per 100,000 women that screening mammograms found would ever have progressed to a dangerous stage. That means that 132, or 81 percent, of the 162 extra tumors detected represented overdiagnosis, that resulted to treatment of tumors that were never destined to harm.

Most importantly, the incidence of metastatic cancer, which is the type that causes most deaths, was flat. 

In conclusion the findings from this study indicate that screening mammography finds many small cancers the dogma that all will grow, metastasize resulting in fatality is questionable. The authors also suggest that although screening may decrease cancer mortality as reflected by the declining incidence of larger tumors, they believe that the two thirds reduction in breast cancer mortality is due to recent advances in treatment. 

N Engl J Med 2016; 375:1438-1447

U.S is Spending $4 billion Annually Resulting from False Positive Mammograms and Unnecessary Treatments

According to a paper published in Health Affairs by Ong and Mendel the U.S. spends $4 billion a year on unnecessary medical costs due to mammograms that generate false alarms, and on treatment of certain breast tumors unlikely to cause problems.

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They found that costs due to false-positive mammograms and breast cancer over diagnoses among women ages 40–59, based on expenditure data from a major US health care insurance plan for 702,154 women in the years 2011–13.

The average expenditures for each false-positive mammogram, invasive breast cancer, and ductal carcinoma in situ in the twelve months following diagnosis were $852, $51,837 and $12,369, respectively. This translates to a national cost of $4 billion each year.

The cumulative cost is as follows: $2.8 billion resulting from false-positive mammograms and another $1.2 billion attributed to treatment of tumors that grow slowly or not at all, and are unlikely to develop into life-threatening disease during a woman’s lifetime.

Screening has the potential to save lives. However, the economic impact of false-positive mammography results and breast cancer over diagnoses must be considered in the debate about the appropriate populations for screening.

Diagnostic Disagreement among Pathologists Interpreting Breast Biopsies

Elmore et al in their article published in JAMA report their findings on diagnostic disagreement among 115 pathologists compared with a consensus panel.

The participating pathologists independently interpreted 240 cases, that included 23 cases of invasive breast cancer, 73 cases of ductal carcinoma in situ (DCIS), 72 cases with atypical hyperplasia (atypia), and 72 benign cases without atypia. Among the 3 consensus panel members, unanimous agreement of their independent diagnoses was 75%, and concordance with the consensus-derived reference diagnoses was 90.3%.

  

Compared with the consensus-derived reference diagnosis, the overall concordance rate of diagnostic interpretations of participating pathologists was 75.3%. Among invasive carcinoma cases 96% were concordant; among DCIS cases 84% were concordant, with 3% were over interpreted, and 13% were under interpreted; among atypia cases 48% were concordant, with 17% were over interpreted, and 35% were under interpreted; and among benign cases without atypia 87% were concordant. Disagreement with the reference diagnosis was statistically significantly higher among biopsies from women whose breasts were dense on prior mammograms.

In this study overall agreement between the individual pathologists’ interpretations and the expert consensus-derived reference diagnoses-was 75.3 percent, with the highest level of agreement 96 percent for invasive carcinoma and lower levels of agreement for DCIS 87 percent.  However, with atypical ductal hyperplasia the pathologists matched the experts only in 48 percent of the time.