Kathleen I. Pritchard

Selective serotonin reuptake inhibitors and breast cancer mortality in women receiving tamoxifen: a population based cohort study

Objective To characterise whether some selective serotonin reuptake inhibitor (SSRI) antidepressants reduce tamoxifen’s effectiveness by inhibiting its bioactivation by cytochrome P450 2D6 (CYP2D6). Design Population based cohort study. Participants Women living in Ontario aged 66 years or older treated with tamoxifen for breast cancer between 1993 and 2005 who had overlapping treatment with a single SSRI. Main outcome measures Risk of death from breast cancer after completion of tamoxifen treatment, as a function of the proportion of time on tamoxifen during which each SSRI had been co-prescribed. Results Of 2430 women treated with tamoxifen and a single SSRI, 374 (15.4%) died of breast cancer during follow-up (mean follow-up 2.38 years, SD 2.59). After adjustment for age, duration of tamoxifen treatment, and other potential confounders, absolute increases of 25%, 50%, and 75% in the proportion of time on tamoxifen with overlapping use of paroxetine (an irreversible inhibitor of CYP2D6) were associated with 24%, 54%, and 91% increases in the risk of death from breast cancer, respectively (P<0.05 for each comparison). By contrast, no such risk was seen with other antidepressants. We estimate that use of paroxetine for 41% of tamoxifen treatment (the median overlap in our sample) would result in one additional breast cancer death within five years of cessation of tamoxifen for every 19.7 (95% confidence interval 12.5 to 46.3) patients so treated; the risk with more extensive overlap would be greater. Conclusion Paroxetine use during tamoxifen treatment is associated with an increased risk of death from breast cancer, supporting the hypothesis that paroxetine can reduce or abolish the benefit of tamoxifen in women with breast cancer.

HER-2 and Topoisomerase II As Predictors of Response to Chemotherapy

HER2 overexpression or amplification has been shown to be associated with a poor prognostic effect in women with breast cancer. At least eight analyses based on randomized trials have examined the relationship between HER2 and the differential effect of anthracycline compared with non-anthracycline-containing regimens. Only three of these studies were sufficiently powered to show a significant interaction between HER2 and anthracycline- versus non-anthracycline-containing treatments, but because all of the study results tended to be in the same direction, it is not surprising that three recent meta-analyses of published data have suggested that anthracycline-containing regimens provide more benefit than non-anthracycline-containing regimens in women whose tumors are overexpressed or amplified (positive) for HER2. Since topoisomerase II is a known target of the anthracyclines, it has been postulated that this relationship is actually based on the proximity of HER2 to the topoisomerase II alpha gene (TOP2A) in the 17q chromosome. At least four recent studies have suggested that deletion and amplification of the TOP2A gene are associated with poor prognosis and are predictive of greater response to anthracycline-containing than to non-anthracycline-containing regimens. However, in at least one of those studies, HER2 positivity was as or more predictive. Although it has been suggested that HER2 positivity is predictive of better response to higher-dose anthracycline-containing regimens compared with standard anthracycline-containing regimens and to taxane- compared with non-taxane-containing regimens, these relationships have not been robust or consistent. Additional studies will be required to clarify these relationships.

HER2 and TOP2A as predictive markers for anthracycline-containing chemotherapy regimens as adjuvant treatment of breast cancer: a meta-analysis of individual patient data

BACKGROUNDnPrediction of response to anthracycline-based therapy for breast cancer is challenging. We aimed to assess the value of HER2 and TOP2A as predictive markers of response to anthracycline-based adjuvant therapy in patients with early breast cancer.nnnMETHODSnWe did a meta-analysis of individual patient data from five randomised adjuvant trials that compared anthracycline-based regimens with cyclophosphamide, methotrexate, and fluorouracil (CMF) regimens. We assessed the status of HER2 and TOP2A genes with fluorescent in-situ hybridisation. Tumour samples were submitted to an external laboratory for validation. We calculated hazard ratios (HR) to compare event-free survival (EFS) and overall survival in patients receiving anthracycline-based treatment with those receiving CMF in two HER2 cohorts (HER2 amplified and non-amplified tumours) and in three TOP2A cohorts (normal, amplified, and deleted tumours).nnnFINDINGSnWe analysed data for 3452 patients for HER2 and 3102 patients for TOP2A. For EFS, HRs were 0·89 (95% CI 0·79-1·01) for HER2 non-amplified patients and 0·71 (0·58-0·86) for HER2-amplified patients (p(interaction)=0·0485); for overall survival, HRs were 0·91 (95% CI 0·79-1·05) for HER2 non-amplified patients and 0·73 (0·59-0·89) for HER2-amplified patients (p(interaction)=0·0718). In analysis of TOP2A status, HRs for EFS were 0·88 (0·78-1·00) for normal, 0·63 (0·46-0·87) for deleted, and 0·62 (0·43-0·90) for amplified (p(interaction)=0·0513); HRs for overall survival were 0·89 (0·78-1·03) for normal, 0·68 (0·49-0·95) for deleted, and 0·67 (0·46-0·98) for amplified (p(interaction)=0·1608). When patients with TOP2A-deleted and TOP2A-amplified tumours were grouped together (altered cohort) and compared with data from patients with normal TOP2A tumours, HRs for EFS were 0·64 (0·50-0·81) for altered and 0·88 (0·78-1·00) for normal (p(interaction)=0·0183); HRs for overall survival were 0·67 (0·52-0·86) for altered and 0·89 (0·78-1·03) for normal (p(interaction)=0·0455).nnnINTERPRETATIONnAlthough HER2 amplification and combined TOP2A amplification and deletion may have some value in the prediction of responsiveness to anthracycline-based chemotherapy, our findings do not support the use of anthracyclines only in patients with HER2-amplified or TOP2A-aberrated tumours.nnnFUNDINGnAssociazione Italiana Ricerca Cancro, Academy of Finland, Belgian Federation Against Cancer, Cancer Research UK, Les Amis de lInstitut Bordet, Scottish Breast Cancer Trials Group, NCIC Clinical Trials Group, Canadian Cancer Society Research Institute, Danish Council for Strategic Research, Pharmacia-Upjohn (now Pfizer), and Abbott Laboratories.

Incidence and Prognostic Impact of Amenorrhea During Adjuvant Therapy in High-Risk Premenopausal Breast Cancer: Analysis of a National Cancer Institute of Canada Clinical Trials Group Study—NCIC CTG MA.5

PURPOSEnTo investigate the therapeutic impact of chemotherapy-induced amenorrhea in premenopausal patients with breast cancer.nnnPATIENTS AND METHODSnWe conducted a retrospective cohort study of a National Cancer Institute of Canada Clinical Trials Group phase III trial involving premenopausal patients randomized to receive cyclophosphamide, methotrexate, and fluorouracil (CMF), versus intensive cyclophosphamide, epirubicin, and fluorouracil (CEF). The objectives of our study were to describe the incidence of amenorrhea at 6 and 12 months post-random assignment and to determine the association of amenorrhea with relapse-free and overall survival.nnnRESULTSnData on 442 patients were used in our analyses. Despite the higher cumulative dose of cyclophosphamide in the CMF treatment arm, at 6 months post-random assignment, the rate of amenorrhea was higher in the CEF group (relative risk, 1.2; 95% CI, 1.0 to 1.3), with no difference at 12 months. In the receptor-positive subgroup, 6-month amenorrhea rates were not associated with prognosis. In contrast, amenorrhea at 12 months was significantly associated with relapse-free survival (hazard ratio, 0.51; 95% CI, 0.32 to 0.82; P = .005) and overall survival (hazard ratio, 0.40; 95% CI, 0.22 to 0.72; P = .002).nnnCONCLUSIONnLate chemotherapy-induced amenorrhea seems to be associated with improved outcome in patients with premenopausal, receptor-positive breast cancer.

Do adjuvant aromatase inhibitors increase the cardiovascular risk in postmenopausal women with early breast cancer? Meta-analysis of randomized trials.

Despite the advantages from using aromatase inhibitors (AIs) compared with tamoxifen for early breast cancer, an unexpectedly greater number of grade 3 and 4 cardiovascular events (CVAE) (as defined by National Cancer Institute of Canada‐Common Toxicity Criteria [version 2.0] was demonstrated.

Droloxifene, a new antiestrogen: Its role in metastatic breast cancer

Droloxifene, a new antiestrogen, has theoretical advantages over tamoxifen based on preclinical data. These include higher affinity to the estrogen receptor, higher antiestrogenic to estrogenic ratio, and more effective inhibition of cell growth and division in ER positive cell lines, as well as less toxicity, including reduced carcinogenicity in animal models. Droloxifene also exhibits more rapid pharmacokinetics, reaching peak concentrations and being eliminated much more rapidly than tamoxifen. A phase II study compared droloxifene in dosages of 20, 40, and 100 mg daily in postmenopausal women with metastatic, or inoperable recurrent, or primary locoregional breast cancer who had not received prior hormonal therapy. Of 369 patients randomized, 292 were eligible and 268 evaluable for response. Response rates (CR + PR) were 30% in the 20 mg group, 47% in the 40 mg group, and 44% in the 100 mg group (40 mg vs 20 mg, p = 0.02; 100 mg vs 20 mg, p = 0.04; pooled 40 + 100 mg vs 20 mg, p = 0.01). Median response duration also favoured the higher dosages (20 mg group = 12 months; 40 mg group = 15 months; 100 mg group = 18 months). When adjusted for prognostic factors, time to progression was significantly better for the 100 mg (p = 0.01) and the 40 mg (p = 0.02) group compared to the 20 mg group. Droloxifene increased SHBG and suppressed FSH at all dosages and suppressed LH at the 40 and 100 mg dosages. These hormonal effects increased with increasing dosage. Shortterm toxicity was generally mild, and similar to that seen with other antiestrogens. Droloxifene appears active and tolerable. It may have a particular role in situations in which rapid pharmacokinetics, or an increased antiestrogenic to estrogenic ratio, are required.

Risk of Acute Leukemia Following Epirubicin-Based Adjuvant Chemotherapy: A Report From the National Cancer Institute of Canada Clinical Trials Group

PURPOSEnCyclophosphamide, epirubicin, and fluorouracil (CEF), compared with classical cyclophosphamide, methotrexate, and fluorouracil (CMF) chemotherapy. has lead to an improvement in relapse-free and overall survival in premenopausal women with node-positive breast cancer. We undertook this analysis to more accurately define the estimate of risk of secondary acute leukemia (sAL) following epirubicin-containing chemotherapy regimens.nnnPATIENTS AND METHODSnWe assessed the conditional probability of sAL among 1,545 women who received adjuvant (n = 1,477) or neoadjuvant (n = 68) chemotherapy in four National Cancer Institute of Canada Clinical Trials Group trials from 1990 to 1999. The risks associated with epirubicin-containing regimens (CEF or epirubicin and cyclophosphamide [EC]) and other regimens (doxorubicin and cyclophosphamide [AC] or CMF) were determined.nnnRESULTSnA total of 10 cases of sAL were observed (eight acute myelogeneous leukemia, two acute lymphoblastic leukemia): seven among women treated with CEF, two who had received AC, and one following CMF. Using competing risk statistics, the conditional probability of sAL was 1.7% (95% confidence interval [CI], 0.5 to 3.6) among 539 women treated with CEF chemotherapy at a follow-up of 8 years, 0.4% (95% CI, 0% to 1.3%) among the 678 who received CMF, and 1.3% (95% CI, 0% to 4.7%) among the 231 treated with AC. The conditional probability of death from breast cancer at 8 years for the entire group of women treated with epirubicin-containing regimens in all four trials was approximately 34.9%.nnnCONCLUSIONnCEF chemotherapy for breast cancer carries a small increased risk of sAL compared with CMF. These estimates of acute leukemia risk are important in discussing treatment with women, especially patients with a lower risk of death from breast cancer, such as those with node-negative breast cancer.

Aromatase inhibitors in adjuvant therapy for hormone receptor positive breast cancer: a systematic review.

BACKGROUNDnA systematic review was undertaken to review the evidence for the use of third-generation aromatase inhibitors (anastrozole, letrozole and exemestane) as adjuvant therapy for post-menopausal women with early-stage, hormone receptor-positive breast cancer and to develop and support recommendations for their use, with regard to three areas: aromatase inhibitors compared to tamoxifen, aromatase inhibitors in sequence with tamoxifen for a total of five years, and aromatase inhibitors given after five years of tamoxifen therapy.nnnMETHODSnMEDLINE, EMBASE, American Society of Clinical Oncology and San Antonio Breast Cancer Symposium proceedings, and the Cochrane Library were searched to May 2007 for reports of randomized controlled trials that met the inclusion criteria.nnnRESULTSnNine randomized controlled trials and one meta-analysis of three of these trials were identified that reported efficacy data. Eight of these trials reported significantly improved disease-free survival in the arms that involved aromatase inhibitors. The meta-analysis reported significantly improved overall survival among all patients, as did one individual trial. One trial of five years letrozole or placebo after five years tamoxifen found improved overall survival among node-positive patients.nnnCONCLUSIONSnAromatase inhibitors provide an alternative to tamoxifen as adjuvant therapy for post-menopausal, hormone-receptor-positive breast cancer patients. The options include anastrozole and letrozole for five years, as well as anastrozole and exemestane following two to three years of tamoxifen, for a total five years of hormonal therapy. Five years of letrozole should be considered following five years of tamoxifen. Patients receiving aromatase inhibitors should be monitored for changes in bone mineral density and for cardiovascular disease risk factors and outcomes.

20-Year Risks of Breast-Cancer Recurrence after Stopping Endocrine Therapy at 5 Years

BACKGROUND The administration of endocrine therapy for 5 years substantially reduces recurrence rates during and after treatment in women with early‐stage, estrogen‐receptor (ER)–positive breast cancer. Extending such therapy beyond 5 years offers further protection but has additional side effects. Obtaining data on the absolute risk of subsequent distant recurrence if therapy stops at 5 years could help determine whether to extend treatment. METHODS In this meta‐analysis of the results of 88 trials involving 62,923 women with ER‐positive breast cancer who were disease‐free after 5 years of scheduled endocrine therapy, we used Kaplan–Meier and Cox regression analyses, stratified according to trial and treatment, to assess the associations of tumor diameter and nodal status (TN), tumor grade, and other factors with patients outcomes during the period from 5 to 20 years. RESULTS Breast‐cancer recurrences occurred at a steady rate throughout the study period from 5 to 20 years. The risk of distant recurrence was strongly correlated with the original TN status. Among the patients with stage T1 disease, the risk of distant recurrence was 13% with no nodal involvement (T1N0), 20% with one to three nodes involved (T1N1–3), and 34% with four to nine nodes involved (T1N4–9); among those with stage T2 disease, the risks were 19% with T2N0, 26% with T2N1–3, and 41% with T2N4–9. The risk of death from breast cancer was similarly dependent on TN status, but the risk of contralateral breast cancer was not. Given the TN status, the factors of tumor grade (available in 43,590 patients) and Ki‐67 status (available in 7692 patients), which are strongly correlated with each other, were of only moderate independent predictive value for distant recurrence, but the status regarding the progesterone receptor (in 54,115 patients) and human epidermal growth factor receptor type 2 (HER2) (in 15,418 patients in trials with no use of trastuzumab) was not predictive. During the study period from 5 to 20 years, the absolute risk of distant recurrence among patients with T1N0 breast cancer was 10% for low‐grade disease, 13% for moderate‐grade disease, and 17% for high‐grade disease; the corresponding risks of any recurrence or a contralateral breast cancer were 17%, 22%, and 26%, respectively. CONCLUSIONS After 5 years of adjuvant endocrine therapy, breast‐cancer recurrences continued to occur steadily throughout the study period from 5 to 20 years. The risk of distant recurrence was strongly correlated with the original TN status, with risks ranging from 10 to 41%, depending on TN status and tumor grade. (Funded by Cancer Research UK and others.)

A meta-analysis of phase III trials evaluating the predictive value of HER2 and topoisomerase II alpha in early breast cancer patients treated with CMF or anthracycline-based adjuvant therapy.

CTRC-AACR San Antonio Breast Cancer Symposium: 2008 AbstractsnnAbstract #705 nnBackground: Retrospective studies have suggested that HER2 and topoisomerase II α (TOP2A) might predict sensitivity to anthracyclines (A) Methods: Four phase III trials comparing A with CMF in early breast cancer (EBC) patients (pts), and with available primary tumor samples, were identified. HER2 and TOP2A genes were evaluated locally by FISH (amplification if ratio ≥ 2). Data were centralized at the statistical office (IDDI, Belgium). On-site visits were performed to check data quality and laboratory procedures. HER2 and TOP2A local scores were validated by submitting randomly selected samples to a central lab (CL) (University of Tampere – Finland), for a 3 color FISH test (HER2, TOP2A, centromere 17, Abbott Labs, IL, USA). Estrogen (ER), progesterone (PgR) receptors, and grade (G) were evaluated locally (no score validation at the CL). Results: We present the results of the planned interim analysis on 1944 pts. Final results (± 3500 pts) will be presented when tumor sample collection for the UK trial is complete. HER2 local scores were validated at the CL in 137 cases (discordance: 8/137, 5.8%). TOP2A local scores were validated in 123 cases (discordance 38/123, 30.8%). Half of the TOP2A discordant cases were locally deleted-centrally normal or vice versa. ![][1] A planned exploratory analysis evaluated the TOP2A predictivity in 4 biologically homogeneous groups: highly or moderately hormone sensitive, HER2+ and ER/PgR negative, triple negative (TN). This analysis did not enhance the TOP2A predictivity in any of the 4 groups. In the TN group (294 pts), the DFS HR was 0.77 (0.54-1.09), suggesting that benefit from A might not be confined to HER2+ pts. Conclusions: The interim analysis shows that HER2 and TOP2A have a clinically modest and a statistically borderline predictive value. In triple negative disease A may be superior to CMF. Acknowledgments: Abbott Laboratories, Belgian Federation Against Cancer, Cancer Research UK, Les Amis de lInstitut Bordet, Pfizer, Scottish BC trials group.nnCitation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 705.nn [1]: /embed/graphic-1.gif