IBIS-I tamoxifen update: maturity brings questions

Breast Cancer Risk Assessment Tool (BCRAT) and long-term breast cancer mortality in the Women's Health Initiative

BACKGROUND

While the Breast Cancer Risk Assessment Tool (BCRAT) predicts breast cancer incidence, the model's performance, re-purposed to predict breast cancer mortality, is uncertain. Therefore, we examined whether the BCRAT model predicts breast cancer mortality in postmenopausal women in the Women's Health Initiative (WHI).

METHODS

BCRAT 5-year breast cancer incidence risk estimates were calculated for 145,408 women (aged 50-79 years) enrolled in the WHI at 40 US clinical centers to examine associations of BCRAT risk groups (< 1%, 1-< 3%, ≥ 3%) with breast cancer mortality using Cox proportional regression modeling in all participants and in those with incident breast cancer.

RESULTS

Women with BCRAT ≥ 3% risk, compared to women with BCRAT < 1% risk, were older (age 70-79 years: 38.3% versus 5.3%), less commonly Black (1.1% versus 40.2%), and had stronger breast cancer family history. With 20-years follow-up, considering all participants, with 8,849 breast cancers and 1,076 breast cancer deaths, breast cancer mortality in BCRAT group ≥ 3% was not higher versus BCRAT group < 1% (Hazard Ratio [HR] 1.06 95% Confidence Interval [CI] 0.80-1.40): percent without 20-year breast cancer mortality; 99.4% [group < 1%] and 98.8% [group ≥ 3%]. Considering women with incident breast cancer, breast cancer mortality was also not higher in BCRAT group ≥ 3% versus BCRAT group < 1% (HR 1.07 95% CI 0.79-1.45).

CONCLUSIONS

The BCRAT model, at ≥ 3% 5-year incidence risk (US guideline threshold for chemoprevention), does not identify women with higher breast cancer mortality risk, with implications for breast cancer prevention strategies.

Breast Cancer Prevention: Time for Change

Agency breast cancer prevention guidelines for other than hereditary cancers have not materially changed in 20 years; endocrine-targeted agents (then, tamoxifen; now, adding raloxifene and aromatase inhibitors) reduce good prognosis estrogen receptor (ER)-positive, progesterone receptor (PR)-positive cancers without reducing deaths from breast cancer. Across three tamoxifen placebo-controlled prevention trials (N = 23,360) begun almost 30 years ago, although there were 226 fewer breast cancer cases, there were nine more deaths from breast cancer in the tamoxifen groups. Following clinical advances, currently more than half of breast cancer cases are solved problems with extremely low risk of death. As endocrine-targeted agents commonly prevent these cancers, widespread implementation of current prevention strategies may not reduce deaths from breast cancer. Compared with other breast cancers, ER-positive, PR-negative cancers and triple-negative cancers have inferior survival (90.6% v 83.8% v 78.1%, respectively; P < .001). Against this background, in the Women's Health Initiative Dietary Modification randomized trial (N = 48,835), ER-positive, PR-negative cancers were statistically significantly reduced in the intervention group (hazard ratio, 0.77; 95% CI, 0.64 to 0.94) and deaths from breast cancer were reduced 21% (P = .02). In the Women's Health Initiative randomized, placebo-controlled trial evaluating conjugated equine estrogen (N = 10,739), ER-positive, PR-negative cancers were statistically significantly reduced in the intervention group (hazard ratio, 0.44; 95% CI, 0.27 to 0.74) and deaths from breast cancer were reduced 40% (P = .04). These findings suggest that reexamination of breast cancer risk reduction strategies and clinical practice is needed.

Low-fat dietary pattern and breast cancer mortality by metabolic syndrome components: a secondary analysis of the Women's Health Initiative (WHI) randomised trial

BACKGROUND

In the Women's Health Initiative (WHI) dietary modification (DM) randomised trial, the low-fat dietary intervention reduced deaths from breast cancer (P = 0.02). Extending these findings, secondary analysis examined dietary intervention influence on breast cancer mortality by metabolic syndrome (MS) components.

METHODS

In total, 48,835 postmenopausal women with no prior breast cancer were randomised to a low-fat dietary intervention or comparison groups. Four MS components were determined at entry in 45,833 participants: (1) high waist circumference, (2) high blood pressure, (3) high cholesterol and (4) diabetes history. Forest plots of hazard ratios (HRs) were generated with P-values for interaction between randomisation groups and MS component score. Primary outcome was death from breast cancer by metabolic syndrome score.

RESULTS

HRs and 95% confidence intervals (CI) for dietary intervention influence on death from breast cancer were with no MS components (n = 10,639), HR 1.09, 95% CI 0.63-1.87; with 1-2 MS components (n = 30,948), HR 0.80, 95% CI 0.62-1.02; with 3-4 MS components (n = 4,246), HR 0.31, 95% CI 0.14-0.69 (interaction P = 0.01).

CONCLUSIONS

While postmenopausal women with 3-4 MS components were at higher risk of death from breast cancer, those randomised to a low-fat dietary intervention more likely had reduction in this risk.

REGISTRY

ClinicalTrials.gov (NCT00000611).

Understanding low chemoprevention uptake by women at high risk of breast cancer: findings from a qualitative inductive study of women's risk-reduction experiences

BACKGROUND

Chemoprevention is one of several methods that have been developed to help high-risk women reduce their risk of breast cancer. Reasons for the low uptake of chemoprevention are poorly understood. This paper seeks a deeper understanding of this phenomenon by drawing on women's own narratives about their awareness of chemoprevention and their risk-related experiences.

METHODS

This research is based on a parent project that included fifty in-depth, semi-structured interviews with a purposive sample of African American and White women at elevated risk of breast cancer. This specific study draws on the forty-seven interviews conducted with women at high or severe risk of breast cancer, all of whom are eligible to use chemoprevention for breast cancer risk-reduction. Interviews were analyzed using grounded theory methods.

RESULTS

Forty-five percent of participants, and only 21% of African American participants, were aware of chemoprevention options. Women who had seen specialists were more likely to be aware, particularly if they had ongoing specialist access. Aware and unaware women relied on different types of sources for prevention-related information. Those whose main source of information was a healthcare provider were more likely to know about chemoprevention. Aware women used more nuanced information gathering strategies and worried more about cancer. Women simultaneously considered all risk-reduction options they knew about. Those who knew about chemoprevention but were reluctant to use it felt this way for multiple reasons, having to do with potential side effects, perceived extreme-ness of the intervention, similarity to chemotherapy, unknown information about chemoprevention, and reluctance to take medications in general.

CONCLUSIONS

Lack of chemoprevention awareness is a critical gap in women's ability to make health-protective choices. Future research in this field must consider complexities in both women's perspectives on chemoprevention and the reasons they are reluctant to use it.

Association of Menopausal Hormone Therapy With Breast Cancer Incidence and Mortality During Long-term Follow-up of the Women's Health Initiative Randomized Clinical Trials

IMPORTANCE

The influence of menopausal hormone therapy on breast cancer remains unsettled with discordant findings from observational studies and randomized clinical trials.

OBJECTIVE

To assess the association of prior randomized use of estrogen plus progestin or prior randomized use of estrogen alone with breast cancer incidence and mortality in the Women's Health Initiative clinical trials.

DESIGN, SETTING, AND PARTICIPANTS

Long-term follow-up of 2 placebo-controlled randomized clinical trials that involved 27 347 postmenopausal women aged 50 through 79 years with no prior breast cancer and negative baseline screening mammogram. Women were enrolled at 40 US centers from 1993 to 1998 with follow-up through December 31, 2017.

INTERVENTIONS

In the trial involving 16 608 women with a uterus, 8506 were randomized to receive 0.625 mg/d of conjugated equine estrogen (CEE) plus 2.5 mg/d of medroxyprogesterone acetate (MPA) and 8102, placebo. In the trial involving 10 739 women with prior hysterectomy, 5310 were randomized to receive 0.625 mg/d of CEE alone and 5429, placebo. The CEE-plus-MPA trial was stopped in 2002 after 5.6 years' median intervention duration, and the CEE-only trial was stopped in 2004 after 7.2 years' median intervention duration.

MAIN OUTCOMES AND MEASURES

The primary outcome was breast cancer incidence (protocol prespecified primary monitoring outcome for harm) and secondary outcomes were deaths from breast cancer and deaths after breast cancer.

RESULTS

Among 27 347 postmenopausal women who were randomized in both trials (baseline mean [SD] age, 63.4 years [7.2 years]), after more than 20 years of median cumulative follow-up, mortality information was available for more than 98%. CEE alone compared with placebo among 10 739 women with a prior hysterectomy was associated with statistically significantly lower breast cancer incidence with 238 cases (annualized rate, 0.30%) vs 296 cases (annualized rate, 0.37%; hazard ratio [HR], 0.78; 95% CI, 0.65-0.93; P = .005) and was associated with statistically significantly lower breast cancer mortality with 30 deaths (annualized mortality rate, 0.031%) vs 46 deaths (annualized mortality rate, 0.046%; HR, 0.60; 95% CI, 0.37-0.97; P = .04). In contrast, CEE plus MPA compared with placebo among 16 608 women with a uterus was associated with statistically significantly higher breast cancer incidence with 584 cases (annualized rate, 0.45%) vs 447 cases (annualized rate, 0.36%; HR, 1.28; 95% CI, 1.13-1.45; P < .001) and no significant difference in breast cancer mortality with 71 deaths (annualized mortality rate, 0.045%) vs 53 deaths (annualized mortality rate, 0.035%; HR, 1.35; 95% CI, 0.94-1.95; P= .11).

CONCLUSIONS AND RELEVANCE

In this long-term follow-up study of 2 randomized trials, prior randomized use of CEE alone, compared with placebo, among women who had a previous hysterectomy, was significantly associated with lower breast cancer incidence and lower breast cancer mortality, whereas prior randomized use of CEE plus MPA, compared with placebo, among women who had an intact uterus, was significantly associated with a higher breast cancer incidence but no significant difference in breast cancer mortality.

Dietary Modification and Breast Cancer Mortality: Long-Term Follow-Up of the Women's Health Initiative Randomized Trial

PURPOSE

Observational studies of dietary fat intake and breast cancer have reported inconsistent findings. This topic was addressed in additional analyses of the Women's Health Initiative (WHI) Dietary Modification (DM) clinical trial that evaluated a low-fat dietary pattern influence on breast cancer incidence.

METHODS

In the WHI DM trial, 48,835 postmenopausal women, ages 50-79 years, with no prior breast cancer, and a dietary fat intake of ≥ 32% of energy were randomly assigned at 40 US centers to a usual diet comparison group (60%) or dietary intervention group (40%). The goals were to reduce fat intake to 20% of energy and increase vegetable, fruit, and grain intake. Breast cancers were confirmed after central medical record review and serial National Death Index linkages to enhance mortality findings.

RESULTS

During 8.5 years of dietary intervention, breast cancer incidence and deaths as a result of breast cancer were nonsignificantly lower in the intervention group, while deaths after breast cancer were statistically significantly lower both during intervention and through a 16.1-year (median) follow-up. Now, after a long-term, cumulative 19.6-year (median) follow-up, the significant reduction in deaths after breast cancer persists (359 [0.12%] v 652 [0.14%] deaths; hazard ratio [HR], 0.85; 95% CI, 0.74 to 0.96; P = .01), and a statistically significant reduction in deaths as a result of breast cancer (breast cancer followed by death attributed to the breast cancer) emerged (132 [0.037%, annualized risk] v 251 [0.047%] deaths, respectively; HR, 0.79; 95% CI, 0.64 to 0.97; P = .02).

CONCLUSION

Adoption of a low-fat dietary pattern associated with increased vegetable, fruit, and grain intake, demonstrably achievable by many, may reduce the risk of death as a result of breast cancer in postmenopausal women.

In Situ-Induced Multivalent Anticancer Drug Clusters in Cancer Cells for Enhancing Drug Efficacy

Increasing intracellular drug concentration is an effective way for cancer chemotherapeutics to enhance efficacy and combat drug resistance. In this work, a series of anticancer drug conjugates were prepared by linking thiol-modified oligo( p-phenylene vinylene) with paclitaxel, vincristine, teniposide, tamoxifen, doxorubicin, or podophyllotoxin (OPV-S-Drugs) through a Michael addition reaction. These OPV-S-Drugs could undergo intracellular assembly and aggregation upon oxidation to yield multivalent anticancer drug clusters, which inhibited their diffusion from cancer cells. The intracellular aggregation of OPV-S-Drugs originates from π–π stacking and hydrophobic interactions between OPV backbones, followed by cross-linking via disulfide bond formation in the presence of reactive oxygen species (ROS). The drug clusters occur only in the cytoplasm of cancer cells expressing high ROS levels, but not in healthy mammalian cells, thus reducing the cytotoxicity to normal cells. Specifically, the super-toxicity of podophyllotoxin to normal cells was obviously suppressed while the drug efficacy was maintained through our new strategy. The diverse action mechanisms of OPV-S-Drugs toward cancer cells is proposed.

Low-Fat Dietary Pattern and Breast Cancer Mortality in the Women's Health Initiative Randomized Controlled Trial

Purpose Earlier Women's Health Initiative Dietary Modification trial findings suggested that a low-fat eating pattern may reduce breast cancers with greater mortality. Therefore, as a primary outcome-related analysis from a randomized prevention trial, we examined the long-term influence of this intervention on deaths as a result of and after breast cancer during 8.5 years (median) of dietary intervention and cumulatively for all breast cancers diagnosed during 16.1 years (median) of follow-up. Patients and Methods The trial randomly assigned 48,835 postmenopausal women with normal mammograms and without prior breast cancer from 1993 to 1998 at 40 US clinical centers to a dietary intervention with goals of a reduction of fat intake to 20% of energy and an increased intake of fruits, vegetables, and grains (40%; n = 19,541) or to a usual diet comparison (60%; n = 29,294). Results In the dietary group, fat intake and body weight decreased (all P < .001). During the 8.5-year dietary intervention, with 1,764 incident breast cancers, fewer deaths occurred as a result of breast cancer in the dietary group, which was not statistically significant (27 deaths [0.016% per year] v 61 deaths [0.024% per year]; hazard ratio [HR], 0.67; 95% CI, 0.43 to 1.06; P = .08). During the same period, deaths after breast cancer (n = 134) were significantly reduced (40 deaths [0.025% per year] v 94 deaths [0.038% per year]; HR, 0.65; 95% CI, 0.45 to 0.94; P = .02) by the dietary intervention. During the 16.1-year follow-up, with 3,030 incident breast cancers, deaths after breast cancer also were significantly reduced (234 deaths [0.085% per year] v 443 deaths [0.11% per year]; HR, 0.82; 95% CI, 0.70 to 0.96; P = .01) in the dietary group. Conclusion Compared with a usual diet comparison group, a low-fat dietary pattern led to a lower incidence of deaths after breast cancer.

Decision making for breast cancer prevention among women at elevated risk

Several medical management approaches have been shown to be effective in preventing breast cancer and detecting it early among women at elevated risk: 1) prophylactic mastectomy; 2) prophylactic oophorectomy; 3) chemoprevention; and 4) enhanced screening routines. To varying extents, however, these approaches are substantially underused relative to clinical practice recommendations. This article reviews the existing research on the uptake of these prevention approaches, the characteristics of women who are likely to use various methods, and the decision-making processes that underlie the differing choices of women. It also highlights important areas for future research, detailing the types of studies that are particularly needed in four key areas: documenting women's perspectives on their own perceptions of risk and prevention decisions; explicit comparisons of available prevention pathways and their likely health effects; the psychological, interpersonal, and social processes of prevention decision making; and the dynamics of subgroup variation. Ultimately, this research could support the development of interventions that more fully empower women to make informed and values-consistent decisions, and to move towards favorable health outcomes.

[Hormonotherapy for breast cancer prevention: What about women with genetic predisposition to breast cancer?]

In France, women carrying BRCA1/2 mutation, at an identified high risk of breast cancer are recommended to undergo breast MRI screening. That screening does not however prevent the risk of developing a breast cancer. The only alternative to breast cancer screening available in France is surgical prevention by prophylactic mastectomy. An interesting option for women who wish to reduce their breast cancer risk, but are unready for prophylactic mastectomy is a preventive hormonal treatment by aromatase inhibitors, or selective estrogens receptor modulators (SERMs). Reliable clinical trials show the efficiency of tamoxifen, raloxifen, exemestane, and anastrozole especially, in reducing breast cancer incidence by 33%, 34%, 65% and 53% respectively. This article tries to sum up the main published trials of breast cancer prevention with hormonal treatment, and presents the latest American and English clinical guidelines concerning hormonal prevention for women at high risk of breast cancer, and starts thinking about the possibilities of hormonoprevention, especially among women carrying a BRCA1/2 mutation in France.

Alternate dosing schedules for cancer chemopreventive agents

Pharmacologic interventions for cancer risk reduction involve the chronic administration of synthetic or natural agents to reduce or delay the occurrence of malignancy. Despite the strong evidence for a favorable risk-benefit ratio for a number of agents in several common malignancies such as breast and prostate cancer, the public's attitude toward cancer chemoprevention remains ambivalent, with the issue of toxicity associated with drugs being perceived as the main barrier to widespread use of preventive therapy by high-risk subjects. Among the strategies to overcome such obstacles to preventive therapies, two novel and potentially safer modes of administering agents are discussed in this paper. The first strategy is to lower the dose of drugs that are in common use in the adjuvant setting based on the notion that prevention of cancer cells from developing should require a lower dose than eradicating established tumor cells. A second approach is to adopt an intermittent administration similar to what is used in the chemotherapy setting in an attempt to minimize risks while retaining benefits. This article provides a detailed discussion of the principles and future development of these two approaches in the direction of a precision preventive medicine.