Abstract P1-07-10: Increasing population rates of in-situ breast cancer [DCIS] are associated with reduced breast cancer (BrCa) mortality. A case for screening mammography and "overdiagnosis" linked to outcome benefits

INTRODUCTION:

Following the first phase of this project [Ref 1], we correlate here the rates of DCIS with BrCaMOR, in two regions of Canada - British Columbia [BC] and Atlantic Provinces [Atl.P].

We previously reported higher compliance in screening mammography [ScreenMam] and therapeutic [TH*] guidelines [GUIDELINES] for both DCIS and invasive BrCa in BC compared with Atl.P [Ref. 2].

METHODS: Annual age-specific rates [cases / 100,000 population] of DCIS, and BrCaMOR between BC vs Atl.P, were obtained for 17 age groups of 5 years (years 0-4 to 85+) and averaged each 5-year period from 1975-1979 up to 2005-2009. To compare age distribution, DCIS rates and BrCaMOR between the two regions, we selected four birth cohorts, age 30-34, 35-39, 40-44 and 45-49 in 1975-1979. From those, we tabulated the DCIS incidence and BrCaMOR for each birth cohort when they reached ages 50-54 and 60-64. We assumed that the rates of DCIS reflect annual ScreenMam practices.

Data were obtained from the Public Health Agency of Canada based on the Canadian Cancer Registry database at Statistics Canada.

RESULTS [N/100,000 population]British ColumbiaAtlantic ProvincesAge / years DCISBrCaMORDCISBrCaMORAge 50 â– 54  1980-8413.152.24.056.41985-8921.246.68.056.11990â–9429.244.421.449.91995â–9945.543.830.050.1Age 60â – 64  1990-9428.072.123.186.21995-9949.361.935.276.62000-0449.365.845.669.42005â–0951.453.141.059.4

CONCLUSIONS:

1. Our study shows across all age cohorts higher rates of DCIS and lower BrCaMOR in BC compared to Atl.P - results consistent with higher ScreenMam rates in BC than Atl.P.

2. These data are compatible with the concept that a higher diagnostic rate for early lesions such as DCIS [i.e. frequently designated as "Overdiagnosis"] by ScreenMam, and subsequent earlier Guideline TH*, contributes to lower BrCaMOR.

*TH Guidelines: surgery, radiation, Tamoxifen for DCIS; and the same + chemotherapy for early invasive disease.

Citation Format: Ragaz J, Qian H, Shakeraneh S, Fox J, Wilson KS, Simpson JS, Yoon J-Y, Wong H. Increasing population rates of in-situ breast cancer [DCIS] are associated with reduced breast cancer (BrCa) mortality. A case for screening mammography and "overdiagnosis" linked to outcome benefits. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P1-07-10.

References:

1. J. Ragaz, H. Wong, H. Qian, J.Fox, K. Wilson, A. Coldman: Cancer Research, May 1, 2015 75; P3-07-28

2. J. Ragaz, H. Wong, H. Qian: Cancer Research Feb 2010; 69(24 Supplement):2063-2063.

MAVEN observations of the response of Mars to an interplanetary coronal mass ejection

Coupling between the lower and upper atmosphere, combined with loss of gas from the upper atmosphere to space, likely contributed to the thin, cold, dry atmosphere of modern Mars. To help understand ongoing ion loss to space, the Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft made comprehensive measurements of the Mars upper atmosphere, ionosphere, and interactions with the Sun and solar wind during an interplanetary coronal mass ejection impact in March 2015. Responses include changes in the bow shock and magnetosheath, formation of widespread diffuse aurora, and enhancement of pick-up ions. Observations and models both show an enhancement in escape rate of ions to space during the event. Ion loss during solar events early in Mars history may have been a major contributor to the long-term evolution of the Mars atmosphere.

Early MAVEN Deep Dip campaign reveals thermosphere and ionosphere variability

The Mars Atmosphere and Volatile Evolution (MAVEN) mission, during the second of its Deep Dip campaigns, made comprehensive measurements of martian thermosphere and ionosphere composition, structure, and variability at altitudes down to ~130 kilometers in the subsolar region. This altitude range contains the diffusively separated upper atmosphere just above the well-mixed atmosphere, the layer of peak extreme ultraviolet heating and primary reservoir for atmospheric escape. In situ measurements of the upper atmosphere reveal previously unmeasured populations of neutral and charged particles, the homopause altitude at approximately 130 kilometers, and an unexpected level of variability both on an orbit-to-orbit basis and within individual orbits. These observations help constrain volatile escape processes controlled by thermosphere and ionosphere structure and variability.

Evaluation of the ToxRTool's ability to rate the reliability of toxicological data for human health hazard assessments

Regulatory agencies often utilize results from peer reviewed publications for hazard assessments. A problem in doing so is the lack of well-accepted tools to objectively, efficiently and systematically assess the quality of published toxicological studies. Herein, we evaluated the publicly available software-based ToxRTool (Toxicological data Reliability assessment Tool) for use in human health hazard assessments. The ToxRTool was developed by the European Commission's Joint Research Center in 2009. It builds on Klimisch categories, a rating system established in 1997, by providing additional criteria and guidance for assessing the reliability of toxicological studies. It also transparently documents the study-selection process. Eight scientists used the ToxRTool to rate the same 20 journal articles on thyroid toxicants. Results were then compared using the Finn coefficient and "AC1" to determine inter-rater consistency. Ratings were most consistent for high-quality journal articles, but less consistent as study quality decreased. Primary reasons for inconsistencies were that some criteria were subjective and some were not clearly described. It was concluded, however, that the ToxRTool has potential and, with refinement, could provide a more objective approach for screening published toxicology studies for use in health risk evaluations, although the ToxRTool ratings are primarily based on study reporting quality.

Uptake of tamoxifen in consecutive premenopausal women under surveillance in a high-risk breast cancer clinic

BACKGROUND

Randomised trials of tamoxifen versus placebo indicate that tamoxifen reduces breast cancer risk by approximately 33%, yet uptake is low. Approximately 10% of women in our clinic entered the IBIS-I prevention trial. We assess the uptake of tamoxifen in a consecutive series of premenopausal women not in a trial and explore the reasons for uptake through interviews.

METHODS

All eligible women between 33 and 46 years at ≥17% lifetime risk of breast cancer and undergoing annual mammography in our service were invited to take a 5-year course of tamoxifen. Reasons for accepting (n=15) or declining (n=15) were explored using semi-structured interviews.

RESULTS

Of 1279 eligible women, 136 (10.6%) decided to take tamoxifen. Women >40 years (74 out of 553 (13.4%)) and those at higher non-BRCA-associated risk were more likely to accept tamoxifen (129 out of 1109 (11.6%)). Interviews highlighted four themes surrounding decision making: perceived impact of side effects, the impact of others' experience on beliefs about tamoxifen, tamoxifen as a 'cancer drug', and daily reminder of cancer risk.

CONCLUSIONS

Tamoxifen uptake was similar to previously ascertained uptake in a randomised controlled trial (IBIS-I). Concerns were similar in women who did or did not accept tamoxifen. Decision making appeared to be embedded in the experience of significant others.