Maggie Wilcox

Bio: Maggie Wilcox is an academic researcher from University of Cambridge. The author has contributed to research in topics: Breast cancer & Population. The author has an hindex of 13, co-authored 29 publications receiving 2813 citations.

The benefits and harms of breast cancer screening: an independent review

Abstract: © 2013 Cancer Research UK. All rights reserved. 1.1 Introduction: The breast cancer screening programmes in the United Kingdom currently invite women aged 50-70 years for screening mammography every 3 years. Since the time the screening programmes were established, there has been debate, at times sharply polarised, over the magnitude of their benefit and harm, and the balance between them. The expected major benefit is reduction in mortality from breast cancer. The major harm is overdiagnosis and its consequences; overdiagnosis refers to the detection of cancers on screening, which would not have become clinically apparent in the woman's lifetime in the absence of screening. Professor Sir Mike Richards, National Cancer Director, England, and Dr Harpal Kumar, Chief Executive Officer of Cancer Research UK, asked Professor Sir Michael Marmot to convene and chair an independent panel to review the evidence on benefits and harms of breast screening in the context of the UK breast screening programmes. The panel, authors of this report, reviewed the extensive literature and heard testimony from experts in the field who were the main contributors to the debate. The nature of information communicated to the public, which too has sparked debate, was not part of the terms of reference of the panel, which are listed in Appendix 1. 1.2 Relative mortality benefit: The purpose of screening is to advance the time of diagnosis so that prognosis can be improved by earlier intervention. A consequence of earlier diagnosis is that it increases the apparent incidence of breast cancer in a screened population and extends the average time from diagnosis to death, even if screening were to confer no benefit. The appropriate measure of benefit, therefore, is reduction in mortality from breast cancer in women offered screening compared with women not offered screening. In the panel's judgement, the best evidence for the relative benefit of screening on mortality reduction comes from 11 randomised controlled trials (RCTs) of breast screening. Meta-analysis of these trials with 13 years of follow-up estimated a 20% reduction in breast cancer mortality in women invited for screening. The relative reduction in mortality will be higher for women actually attending screening, but by how much is difficult to say because women who do not attend are likely to have a different background risk. Three types of uncertainties surround this estimate of 20% reduction in breast cancer mortality. The first is statistical: the 95% confidence interval (CI) around the relative risk (RR) reduction of 20% was 11-27%. The second is bias: there are a number of potential sources of distortion in the trials that have been widely discussed in the literature ranging from suboptimal randomisation to problems in adjudicating cause of death. The third is the relevance of these old trials to the current screening programmes. The panel acknowledged these uncertainties, but concluded that a 20% reduction is still the most reasonable estimate of the effect of the current UK screening programmes on breast cancer mortality. Most other reviews of the RCTs have yielded similar estimates of relative benefit. The RCTs were all conducted at least 20-30 years ago. More contemporary estimates of the benefit of breast cancer screening come from observational studies. The panel reviewed three types of observational studies. The first were ecological studies comparing areas, or time periods, when screening programmes were and were not in place. These have generated diverse findings, partly because of the major advances in treatment of breast cancer, which have a demonstrably larger influence on mortality trends than does screening, and partly because of the difficulty of excluding imbalances in other factors that could affect breast cancer mortality. The panel did not consider these studies helpful in estimating the effect of screening on mortality. The other two types of studies, case-control studies and incidence-based mortality studies, showed breast screening to confer a greater benefit than did the trials. Although these studies, in general, attempted to control for non-comparability of screened and unscreened women, the panel was concerned that residual bias could inflate the estimate of benefit. However, the panel notes that these studies' findings are in the same direction as the trials. 1.3 Absolute mortality benefit: Estimates of absolute benefit of screening have varied from one breast cancer death avoided for 2000 women invited to screening to 1 avoided for about 100 women screened, about a 20-fold difference. Major determinants of that large variation are the age of women screened, and the durations of screening and follow-up. The age of the women invited is important, as mortality from breast cancer increases markedly with age. The panel therefore applied the relative mortality reduction of 20% to achieve the observed cumulative absolute risk of breast cancer mortality over the ages 55-79 years for women in the United Kingdom, assuming that women who began screening at 50 years would gain no benefit in the first 5 years, but that the mortality reduction would continue for 10 years after screening ended. This yielded the estimate that for every 235 women invited to screening, one breast cancer death would be prevented; correspondingly 180 women would need to be screened to prevent one breast cancer death. Uncertainties in the figure of a 20% RR reduction would carry through to these estimates of absolute mortality benefit. Nonetheless, the panel's estimate of benefit is in the range of one breast cancer death prevented for B250 women invited, rather than the range of 1 in 2000. 1.4 Overdiagnosis: The major harm of screening considered by the panel was that of overdiagnosis. Given the definition of an overdiagnosed cancer, either invasive or non-invasive, as one diagnosed by screening, which would not otherwise have come to attention in the woman's lifetime, there is need for a long follow-up to assess the frequency of overdiagnosis. In the view of the panel, some cancers detected by screening will be overdiagnosed, but the uncertainty surrounding the extent of overdiagnosis is greater than that for the estimate of mortality benefit because there are few sources of reliable data. The issue for the UK screening programmes is the magnitude of overdiagnosis in women who have been in a screening programme from age 50 to 70, then followed for the rest of their lives. There are no data to answer this question directly. Any estimate will therefore be, at best, provisional. Although the definition of an overdiagnosed case, and thus the numerator in a ratio, is clear, the choice of denominator has been the source of further variability in published estimates. Different studies have used: only the cancers found by screening; cancers found during the whole screening period, both screen-detected and interval; cancers diagnosed during the screening period and for the remainder of the women's lifetime. The panel focused on two estimates: the first from a population perspective using as the denominator the number of breast cancers, both invasive and ductal carcinoma in situ (DCIS), diagnosed throughout the rest of a woman's lifetime after the age that screening begins, and the second from the perspective of a woman invited to screening using the total number of breast cancers diagnosed during the screening period as the denominator. The panel thought that the best evidence came from three RCTs that did not systematically screen the control group at the end of the screening period and followed these women for several more years. The frequency of overdiagnosis was of the order of 11% from a population perspective, and about 19% from the perspective of a woman invited to screening. Trials that included systematic screening of the control group at the end of the active part of the trial were not considered to provide informative estimates of the frequency of overdiagnosis. Information from observational studies was also considered. One method that has been used is investigation of time trends in incidence rates of breast cancer for different age groups over the period that population screening was introduced. The published results of these studies varied greatly and have been interpreted as providing either reassurance or cause for alarm. So great was the variation in results that the panel conducted an exercise by varying the assumptions and statistical methods underlying these studies, using the same data sets; estimates of overdiagnosis rates were found to vary across the range of 0-36% of invasive breast cancers diagnosed during the screening period. The panel had no reason to favour one set of estimates over another, and concluded that this method could give no reliable estimate of the extent of overdiagnosis. Were it possible to distinguish at screening those cancers that would not otherwise have come to attention from those that, untreated, would lead to death, the overdiagnosis problem could be much reduced, at least in terms of unnecessary worry and treatment. Currently this is not possible, so neither the woman nor her doctor can know whether a screen-detected cancer is an 'overdiagnosed' case or not. In particular, DCIS, most often diagnosed at screening, does not inevitably equate to overdiagnosis - screen-detected DCIS, after wide local excision (WLE) only, is associated with subsequent development of invasive breast cancer in 10% of women within 10 years. The consequences of overdiagnosis matter, women are turned into patients unnecessarily, surgery and other forms of cancer treatment are undertaken, and quality of life and psychological well being are adversely affected.

Chemotherapy and Targeted Therapy for Women With Human Epidermal Growth Factor Receptor 2–Negative (or unknown) Advanced Breast Cancer: American Society of Clinical Oncology Clinical Practice Guideline

Abstract: Purpose To identify optimal chemo- and targeted therapy for women with human epidermal growth factor 2 (HER2)– negative (or unknown) advanced breast cancer. Methods A systematic review of randomized evidence (including systematic reviews and meta-analyses) from 1993 through to current was completed. Outcomes of interest included survival, progression-free survival, response, quality of life, and adverse effects. Guideline recommendations were evidence based and were agreed on by the Expert Panel via consensus. Results Seventy-nine studies met the inclusion criteria, comprising 20 systematic reviews and/or meta-analyses, 30 trials on first-line treatment, and 29 trials on second-line and subsequent treatment. These trials form the evidence base for the guideline recommendations. Recommendations Endocrine therapy is preferable to chemotherapy as first-line treatment for patients with estrogen receptor–positive metastatic breast cancer unless improvement is medically necessary (eg, immediately life-threateni...

Global Cancer Statistics 2020: GLOBOCAN Estimates of Incidence and Mortality Worldwide for 36 Cancers in 185 Countries.

Abstract: This article provides an update on the global cancer burden using the GLOBOCAN 2020 estimates of cancer incidence and mortality produced by the International Agency for Research on Cancer. Worldwide, an estimated 19.3 million new cancer cases (18.1 million excluding nonmelanoma skin cancer) and almost 10.0 million cancer deaths (9.9 million excluding nonmelanoma skin cancer) occurred in 2020. Female breast cancer has surpassed lung cancer as the most commonly diagnosed cancer, with an estimated 2.3 million new cases (11.7%), followed by lung (11.4%), colorectal (10.0 %), prostate (7.3%), and stomach (5.6%) cancers. Lung cancer remained the leading cause of cancer death, with an estimated 1.8 million deaths (18%), followed by colorectal (9.4%), liver (8.3%), stomach (7.7%), and female breast (6.9%) cancers. Overall incidence was from 2-fold to 3-fold higher in transitioned versus transitioning countries for both sexes, whereas mortality varied <2-fold for men and little for women. Death rates for female breast and cervical cancers, however, were considerably higher in transitioning versus transitioned countries (15.0 vs 12.8 per 100,000 and 12.4 vs 5.2 per 100,000, respectively). The global cancer burden is expected to be 28.4 million cases in 2040, a 47% rise from 2020, with a larger increase in transitioning (64% to 95%) versus transitioned (32% to 56%) countries due to demographic changes, although this may be further exacerbated by increasing risk factors associated with globalization and a growing economy. Efforts to build a sustainable infrastructure for the dissemination of cancer prevention measures and provision of cancer care in transitioning countries is critical for global cancer control.

Breast Cancer Treatment: A Review.

Abstract: Importance Breast cancer will be diagnosed in 12% of women in the United States over the course of their lifetimes and more than 250 000 new cases of breast cancer were diagnosed in the United States in 2017. This review focuses on current approaches and evolving strategies for local and systemic therapy of breast cancer. Observations Breast cancer is categorized into 3 major subtypes based on the presence or absence of molecular markers for estrogen or progesterone receptors and human epidermal growth factor 2 (ERBB2; formerlyHER2): hormone receptor positive/ERBB2 negative (70% of patients),ERBB2positive (15%-20%), and triple-negative (tumors lacking all 3 standard molecular markers; 15%). More than 90% of breast cancers are not metastatic at the time of diagnosis. For people presenting without metastatic disease, therapeutic goals are tumor eradication and preventing recurrence. Triple-negative breast cancer is more likely to recur than the other 2 subtypes, with 85% 5-year breast cancer–specific survival for stage I triple-negative tumors vs 94% to 99% for hormone receptor positive andERBB2positive. Systemic therapy for nonmetastatic breast cancer is determined by subtype: patients with hormone receptor–positive tumors receive endocrine therapy, and a minority receive chemotherapy as well; patients withERBB2-positive tumors receiveERBB2-targeted antibody or small-molecule inhibitor therapy combined with chemotherapy; and patients with triple-negative tumors receive chemotherapy alone. Local therapy for all patients with nonmetastatic breast cancer consists of surgical resection, with consideration of postoperative radiation if lumpectomy is performed. Increasingly, some systemic therapy is delivered before surgery. Tailoring postoperative treatment based on preoperative treatment response is under investigation. Metastatic breast cancer is treated according to subtype, with goals of prolonging life and palliating symptoms. Median overall survival for metastatic triple-negative breast cancer is approximately 1 year vs approximately 5 years for the other 2 subtypes. Conclusions and Relevance Breast cancer consists of 3 major tumor subtypes categorized according to estrogen or progesterone receptor expression andERBB2gene amplification. The 3 subtypes have distinct risk profiles and treatment strategies. Optimal therapy for each patient depends on tumor subtype, anatomic cancer stage, and patient preferences.

Triple-negative breast cancer: challenges and opportunities of a heterogeneous disease

Abstract: Chemotherapy is the primary established systemic treatment for patients with triple-negative breast cancer (TNBC) in both the early and advanced-stages of the disease. The lack of targeted therapies and the poor prognosis of patients with TNBC have fostered a major effort to discover actionable molecular targets to treat patients with these tumours. Massively parallel sequencing and other 'omics' technologies have revealed an unexpected level of heterogeneity of TNBCs and have led to the identification of potentially actionable molecular features in some TNBCs, such as germline BRCA1/2 mutations or 'BRCAness', the presence of the androgen receptor, and several rare genomic alterations. Whether these alterations are molecular 'drivers', however, has not been clearly established. A subgroup of TNBCs shows a high degree of tumour-infiltrating lymphocytes that also correlates with a lower risk of disease relapse and a higher likelihood of benefit from chemotherapy. Proof-of-principle studies with immune-checkpoint inhibitors in advanced-stage TNBC have yielded promising results, indicating the potential benefit of immunotherapy for patients with TNBC. In this Review, we discuss the most relevant molecular findings in TNBC from the past decade and the most promising therapeutic opportunities derived from these data.