Rare, evolutionarily unlikely missense substitutions in CHEK2 contribute to breast cancer susceptibility: results from a breast cancer family registry (CFR) case-control mutation screening study

Florence Le Calvez-Kelm , Fabienne Lesueur , Francesca Damiola , Maxime Vallee , Catherine Voegele , Davit Babikyan , Geoffroy Durand , Nathalie Forey , Sandrine McKay-Chopin , Nivonirina Robinot , Tu Nguyen-Dumont , Alun Thomas , Graham B Byrnes , The Breast Cancer Family Registry , John L Hopper , Melissa C Southey , Irene L Andrulis , Esther M John and Sean V Tavtigian

Breast Cancer Research 2011, 13:R6doi:10.1186/bcr2810

Published:	18 January 2011

Abstract (provisional)

Introduction

Both protein truncating variants and some missense substitutions in CHEK2 confer increased risk of breast cancer. However, no large-scale study has used full open reading frame mutation screening to assess the contribution of rare missense substitutions in CHEK2 to breast cancer risk. This absence has been due in part to a lack of validated statistical methods for summarizing risk attributable to large numbers of individually rare missense substitutions.

Methods

Previously, we adapted an in silico assessment of missense substitutions used for analysis of unclassified missense substitutions in BRCA1 and BRCA2 to the problem of assessing candidate genes using rare missense substitution data observed in case-control mutation screening studies. The method involves stratifying rare missense substitutions observed in cases and/ or controls into a series of grades a priori ordered from least to most likely to be evolutionarily deleterious, followed by a logistic regression test for trend to compare the frequency distributions of the graded missense substitutions in cases versus controls. Here we used this approach to analyze CHEK2 mutation screening data from a population based series of 1303 female breast cancer cases and 1109 unaffected female controls.

Results

We found evidence of risk associated with rare, evolutionarily unlikely CHEK2 missense substitutions. Additional findings were: (1) the risk estimate for the most severe grade of CHEK2 missense substitutions (denoted C65) is approximately equivalent to that of CHEK2 protein truncating variants; (2) the population attributable fraction and familial relative risk explained by the pool of rare missense substitutions were similar to those explained by the pool of protein truncating variants; and (3) post-hoc power calculations implied that scaling case-control mutation screening up to examine entire biochemical pathways would require roughly 2,000 cases and controls to achieve acceptable statistical power.

Conclusions

This study shows that CHEK2 harbors many rare sequence variants that confer increased risk of breast cancer, and a substantial proportion of these are missense substitutions. The study validates our analytic approach to rare missense substitutions and provides a method to combine data from protein truncating variants and rare missense substitutions into a one degree of freedom per gene test.

Source : http://breast-cancer-research.com/content/13/1/R6

Annual Breast Cancer Screening Beginning at Age 40 Reduces Mastectomy Risk, Study Finds

ScienceDaily Report

(Dec. 1, 2010) — Having a yearly mammogram greatly reduces the risk of mastectomy following breast cancer in women between the ages of 40 and 50, according to a study presented today at the annual meeting of the Radiological Society of North America (RSNA).

"The results of this study support the importance of regular screening in the 40 to 50 age group," said lead author Nicholas M. Perry, M.B.B.S., F.R.C.S., F.R.C.R., director of The London Breast Institute at The Princess Grace Hospital in London. "Women in this age group who had undergone mammography the previous year had a mastectomy rate of less than half that of the others."

An estimated 207,090 new cases of invasive breast cancer will be diagnosed in American women in 2010. Currently, the American Cancer Society recommends annual mammography screening for women beginning at age 40 in the U.S., but last year, the U.S. Preventive Services Task Force recommended changing the guidelines to begin screening biennially (every other year) at age 50. There are no routine screening guidelines for women under 50 in the U.K.

The researchers studied the benefits of screening women between the ages of 40 and 50, the frequency of mammography and the type of treatment after breast cancer diagnosis.

Dr. Perry and colleagues reviewed the clinical data available on women from 40 to 50 that had been diagnosed with breast cancer and treated at The London Breast Institute. Between 2003 and 2009, 971 women had been diagnosed with breast cancer. At the time of diagnosis, 393 (40 percent) of the women were under 50, with 156 of these women completing treatment at the center. Of the treated women, 114 (73 percent) had no prior mammograms. Forty-two women had been previously screened with mammography, of whom 29 had at least one mammogram within the previous two years. Of those, 16 women had a mammogram one year prior.

"We reviewed the records of the women needing mastectomy to determine whether or not they had undergone mammography the previous year," Dr. Perry said. "We were surprised at the degree of benefit obtained from yearly screening in this age group."

Data showed that mastectomy was the required treatment for 3 (19 percent) of the 16 women who had been screened the prior year, compared to 64 (46 percent) of the 140 women who had not been screened in the past year.

"Regular screening is already proven to lower the chance of women dying from breast cancer," Dr. Perry said. "The results of our study support the importance of regular screening in the under-50 age group and confirm that annual mammography improves the chances of breast conservation should breast cancer develop."

Dr. Perry's coauthors are Sue Milner, B.Sc., D.C.R., Kefah Mokbel, M.B.B.S., M.S., F.R.C.S., Stephen W. Duffy, B.Sc., M.Sc., and Katja Pinker, M.D.

Women With False-positive Mammograms Report High Anxiety And Reduced Quality Of Life

Doctors are calling for women to receive more information about the pitfalls of breast cancer screening, as well as the benefits, after some women who received false-positive results faced serious anxiety and reduced quality of life for at least a year.

A study published online by BJS, the British Journal of Surgery, shows that patients with false-positive results - where the mammogram is abnormal but no cancer is present - had to undergo more diagnostic procedures than women with breast cancer before they were given the all clear. Researchers from The Netherlands spoke to 385 women with abnormal mammogram results - 152 were subsequently diagnosed with breast cancer, but the other 233 had false-positive results and did not have cancer.

"Common sense tells us that early detection of breast cancer is good and most screening programmes have been successful in reducing breast cancer deaths" says lead author Dr Lideke van der Steeg from the Department of Surgery, St Elisabeth Hospital, Tilburg, and the Centre of Research and Psychology in Somatic Diseases, Tilburg University.

"However, while some women truly benefit from early detection, others experience harm and unnecessary anxiety. The women who received false-positives in our study experienced a significant reduction in their quality of life, especially if they were prone to anxiety, and the effects of this lasted at least a year.

"In fact, women who had a tendency to be anxious fared much worse if they received a false-positive - which is estimated to happen in 60 per cent of abnormal mammograms - than if they were actually diagnosed with breast cancer."

Women with abnormal mammograms attending three hospitals over a five-year period were invited to participate. Their quality of life (QoL) was assessed using the World Health Organization's Quality of Life instrument 100, which assesses QoL in six domains physical health, psychological health, level of independence, social relationships, environment and spirituality.

Clinical data were obtained from the women's medical records and they were also asked to complete questionnaires providing demographic information such as age, marital status, education and socioeconomic status.

Women in the breast cancer (BC) group were significantly older than the women in the false-positive (FP) group 60.2 years versus 57.3 years. They also had larger tumours than the FP group 17.4mm versus 9.9mm.

The key factors influencing QoL scores differed between the two groups:

-- Trait anxiety (a tendency to experience anxiety) accounted for up to 55 per cent of the variance in the QoL score in the FP group. It reached this peak at three months, but was similar at months one and 12 (43 per cent and 40 per cent respectively).

-- State anxiety (temporary anxiety due to a specific situation) accounted for up to 46 per cent of the variance in the BC group. It peaked at six months, but was similar in months one and 12 (32 per cent and 34 per cent).

-- State anxiety levels did not significantly influence QoL in the FP group and trait anxiety levels did not influence QoL in the BC group.

Significantly more diagnostic procedures, including biopsies, were needed in the FP group to reach a final diagnosis. Only 14 per cent of the BC group required four procedures - the other 86 per cent required three - while 32 per cent of the FP group required more than three. Fifty-five per cent of the FP group returned to the outpatient clinic in the first year, some as many as eight times.

The authors believe that the anxiety and lower QoL experienced by women in the FP group were soley due to the recall after screening and the subsequent diagnostic procedures.

"The decision to participate in a screening programme requires balanced information about the potential benefits and dangers" says Dr van der Steeg.

"Women often overestimate their risk of breast cancer and the material provided by healthcare professionals and government agencies often focus on the positive aspects of screening and are not always objective.

"Women deserve more balanced information to help them to chose whether or not to accept a breast screening invitation. This should not only cover the supposed benefits, but explain the potential side-effects of a false-positive, such as the increased feelings of anxiety and reduced QoL found by our study."

Sources: Wiley - Blackwell, AlphaGalileo Foundation.

Genetic Predisposition Discovered For Breast, Kidney Cancers

Researchers at Cleveland Clinic's Genomic Medicine Institute have revealed multiple genetic discoveries that may permit easier diagnosis and disease management for Cowden syndrome patients who are predisposed to breast and kidney cancer.

The research, which could allow for earlier discovery of cancerous tumors, is published in the Dec. 22 issue of the Journal of the American Medical Association (JAMA).

Charis Eng, M.D., Ph.D, Chair of the Genomic Medicine Institute at Cleveland Clinic, led the research. It revealed KILLIN as a novel predisposition gene for Cowden syndrome (CS) and Cowden-like syndrome (CLS) features in individuals without germline PTEN mutations, which also plays a role in cancer risk.

According to Dr. Eng, "CLS is at least 10 times more common than CS, but the genetic alteration responsible for CLS and its cancers has eluded the scientific community for more than a decade. From our research, we now know that KILLIN accounts for almost half of CLS, making diagnosis much more accurate."

Mutations in the PTEN gene are the foundation of Cowden syndrome. PTEN is a tumor suppressor gene, helping to direct the growth and division of cells. Inherited mutations in the PTEN gene have been found in approximately 80 percent of Cowden syndrome patients. These mutations prevent the PTEN protein from effectively regulating cell survival and division, which can lead to the formation of tumors.

However, not all CS and CLS patients carry mutated PTEN. In fact, in CLS, less than 10 percent have PTEN mutations, yet they develop cancers just like CS. In those patients without the PTEN mutation, 42 percent of Cowden syndrome patients and 33 percent of Cowden-like syndrome patients have low levels of KILLIN tumor suppressor gene.

"We know that 80 percent of Cowden patients carry the PTEN mutation and half of the remaining 20 percent carry the inactive KILLIN gene," Dr. Eng said. "What that means is that altogether PTEN and KILLIN should account for 90 percent of all cases of classic Cowden syndrome, a huge step forward in diagnosing an often overlooked disease. More importantly, KILLIN and PTEN should account for almost half of CLS individuals."

This study shows that CS/CLS individuals with KILLIN promoter methylation, which switches the KILLIN gene off, have a threefold greater risk of breast cancer, and a twofold greater risk of kidney cancer, compared to those with mutant PTEN. Having the ability to identify these individuals will allow for more proactive management of their health, such as more careful screening and shared best practices among physicians who treat them.

Findings from this study indicate that individuals with classic Cowden syndrome should be offered PTEN testing first; those found not to have PTEN mutations should then be screened for the inactivated KILLIN gene and offered genetic counseling. Those patients who carry neither the PTEN mutation nor the inactive KILLIN gene should be offered additional/alternative genetic testing and importantly, encouraged to participate in research.

Source:
Dan Doron
Cleveland Clinic Foundation

Breast, Kidney Cancers