Francis P. Boscoe, Ph.D, Research Scientist, New York State Cancer Registry (NAACCR at-large Board Member)

This week, a team of researchers published a study using central cancer registry data which found that U.S. counties where 40% of the women met mammography screening guidelines in 2000 had age-adjusted incidence rates of about 200 per 100,000 and ten-year mortality rates of about 50 per 100,000. Counties where 80% of the women met mammography screening guidelines in 2000 (twice as many) had age-adjusted incidence rates of about 350 per 100,000 (almost twice as many) and ten-year mortality rates of about 50 per 100,000 (exactly the same). While they took this as further evidence against the unqualified utility of mammography, they were careful not to overstate the point. Instead, they helpfully concluded:

“As is the case with screening in general, the balance of benefits and harms is likely to be most favorable when screening is directed to those at high risk, provided neither too frequently nor too rarely, and sometimes followed by watchful waiting instead of immediate active treatment”.

Given the very different risk profiles associated with breast cancer subtypes, might we be moving toward a time when screening recommendations are based on more than just age?

“If you haven’t gotten this message already, you should heed it now: The benefits of screening for breast cancer are limited. We should be doing fewer screening mammograms, not more.” …

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Read Full Article (The abstract below is from an article from JAMA Internal Medicine)

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Abstract

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Importance: Screening mammography rates vary considerably by location in the United States, providing a natural opportunity to investigate the associations of screening with breast cancer incidence and mortality, which are subjects of debate.

Objective: To examine the associations between rates of modern screening mammography and the incidence of breast cancer, mortality from breast cancer, and tumor size.

Design, Setting, and Participants: An ecological study of 16 million women 40 years or older who resided in 547 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 followed up for the next 10 years. The study covered the period January 1, 2000, to December 31, 2010, and the analysis was performed between April 2013 and March 2015.

Exposures: Extent of screening in each county, assessed as the percentage of included women who received a screening mammogram in the prior 2 years.

Main Outcomes and Measures: Breast cancer incidence in 2000 and incidence-based breast cancer mortality during the 10-year follow-up. Incidence and mortality were calculated for each county and age adjusted to the US population.

Results: Across US counties, there was a positive correlation between the extent of screening and breast cancer incidence (weighted r = 0.54; P < .001) but not with breast cancer mortality (weighted r = 0.00; P = .98). An absolute increase of 10 percentage points in the extent of screening was accompanied by 16% more breast cancer diagnoses (relative rate [RR], 1.16; 95% CI, 1.13-1.19) but no significant change in breast cancer deaths (RR, 1.01; 95% CI, 0.96-1.06). In an analysis stratified by tumor size, we 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 (RR, 1.25; 95% CI, 1.18-1.32) and a 7% increase in the incidence of larger breast cancers (RR, 1.07; 95% CI, 1.02-1.12).

Conclusions and Relevance: When analyzed at the county level, the clearest result of mammography screening is the diagnosis of additional small cancers. Furthermore, there is 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.

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The opinions expressed in this article are those of the authors and may not represent the official positions of NAACCR.

Hannah K. Weir, Ph.D, Senior Epidemiologist, Centers for Disease Control and Prevention (NAACCR Steering Committee Chair)

In the near future, cancer is predicted to become the leading cause of death in the United States. It’s already the leading cause of premature deaths. Every year, we report the rate of cancer deaths is going down while the number of cancer deaths increases. And that is unlikely to change in coming years, as the proportion of older people – those at greatest risk of dying from cancer – increases. Many of these deaths are avoidable, either by preventing the cancer in the first place or by diagnosing it early and providing high-quality cancer treatment.

How can we address this problem and reduce suffering and death from cancer? CDC and its partners developed cancer mortality objectives for Healthy People (HP) 2020, calling for a 10% to 15% reduction in cancer death rates between 2007 and 2020 for selected cancers.

In a new study, just released in Preventing Chronic Disease, we used population projections and trends in cancer death rates to see if we will meet the HP2020 objectives. Additional information can be found here.

Much of the news is encouraging: from 2007 to 2020, death rates are predicted to continue decreasing and to meet HP2020 objectives for cancers of the female breast, lung and bronchus, cervix and uterus, colon and rectum, oral cavity and pharynx, and prostate. We were disappointed to find that this is not true for melanoma.

Our findings point to the need to increase efforts to promote cancer prevention and improve survival to counter the impact of a growing and aging population on the cancer burden and to meet melanoma target death rates. In the coming years, we will continue to monitor and report on trends in cancer incidence and deaths. This monitoring is particularly important where screening can either prevent cancer (cervical and colorectal cancers) or find it early (cervical, colorectal, and female breast cancers), when treatment can be most effective.

Click here to view original article (The abstract below is from the Centers for Disease Control and Prevention article ‘Meeting the Healthy People 2020 Objectives to Reduce Cancer Mortality’)

Abstract