Platinum chemotherapy for early triple-negative breast cancer

BACKGROUND

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer associated with shorter survival and a higher likelihood of recurrence. In early TNBC, platinum chemotherapy has been shown to improve pathological complete response (pCR); however, its effect on long-term survival outcomes has not been fully elucidated.

METHODS

Randomised controlled trials examining neoadjuvant or adjuvant platinum chemotherapy for early TNBC were included. Primary outcomes were disease-free survival (DFS) and overall survival (OS). Secondary outcomes were pCR, treatment adherence, grade III or IV toxicity related to chemotherapy, and quality of life.

RESULTS

From 3972 records, we included 20 published studies. All studies reporting DFS and OS used carboplatin. Inclusion of platinum chemotherapy improved DFS (neoadjuvant: hazard ratio (HR) 0.63, 95% confidence interval (CI) 0.53 to 0.75; adjuvant: HR 0.69, 95% CI 0.54 to 0.88) and OS (neoadjuvant: HR 0.69, 95% CI 0.55 to 0.86; adjuvant: 0.70, 95% CI 0.50 to 0.96). Our analysis confirmed platinum chemotherapy increased pCR rates (risk ratio (RR) 1.44, 95% CI 1.31 to 1.59). There were no differences seen in examined subgroups. Platinum chemotherapy was associated with reduced dose intensity and increased haematological toxicity.

CONCLUSIONS

Platinum-based chemotherapy using carboplatin in the adjuvant or neoadjuvant setting improves long-term outcomes of DFS and OS in early TNBC, with no evidence of differences by subgroup. This was at the cost of more frequent chemotherapy delays and dose reductions, and greater haematological toxicity. These findings support the use of platinum-based chemotherapy for people with early TNBC.

Platinum-based chemotherapy for early triple-negative breast cancer

BACKGROUND

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer associated with shorter survival and a higher likelihood of the cancer returning. In early TNBC, platinum-based chemotherapy has been shown to improve pathological complete response (pCR); however, its effect on long-term survival outcomes has not been fully elucidated and recommendations to include platinum chemotherapy are not consistent in international guidelines.

OBJECTIVES

To evaluate the benefits and harms of platinum-based chemotherapy as adjuvant and neoadjuvant treatment in people with early triple-negative breast cancer.

SEARCH METHODS

We used standard, extensive Cochrane search methods. The latest search date was 4 April 2022.

SELECTION CRITERIA

We included randomised controlled trials examining neoadjuvant or adjuvant platinum chemotherapy for early TNBC.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. Our primary outcomes were disease-free survival (DFS) and overall survival (OS). Our secondary outcomes were pCR, treatment adherence, grade III or IV toxicity related to chemotherapy, and quality of life. Prespecified subgroups included BRCA mutation status, homologous recombination deficiency (HRD) status, frequency of chemotherapy, type of platinum agent used, and the presence or absence of anthracycline chemotherapy. We assessed risk of bias using Cochrane's RoB 1 tool and certainty of evidence using the GRADE approach.

MAIN RESULTS

From 3972 records, we included 20 published studies involving 21 treatment comparisons, and 25 ongoing studies. For most domains, risk of bias was low across studies. There were 16 neoadjuvant chemotherapy studies (one of which combined neoadjuvant and adjuvant therapy) and four adjuvant chemotherapy trials. Most studies used carboplatin (17 studies) followed by cisplatin (two), and lobaplatin (one). Eight studies had an anthracycline-free intervention arm, five of which had a carboplatin-taxane intervention compared to an anthracycline-taxane control. All studies reporting DFS and OS used carboplatin. Inclusion of platinum chemotherapy improved DFS in neoadjuvant and adjuvant settings (neoadjuvant: hazard ratio (HR) 0.63, 95% confidence interval (CI) 0.53 to 0.75; 7 studies, 8 treatment comparisons, 1966 participants; high-certainty evidence; adjuvant: HR 0.69, 95% CI 0.54 to 0.88; 4 studies, 1256 participants; high-certainty evidence). Platinum chemotherapy in the regimen improved OS (neoadjuvant: HR 0.69, 95% CI 0.55 to 0.86; 7 studies, 8 treatment comparisons, 1973 participants; high-certainty evidence; adjuvant: 0.70, 95% CI 0.50 to 0.96; 4 studies, 1256 participants; high-certainty evidence). Median follow-up for survival outcomes ranged from 36 to 97.6 months. Our analysis confirmed platinum chemotherapy increased pCR rates (risk ratio (RR) 1.44, 95% CI 1.31 to 1.59; 15 studies, 16 treatment comparisons, 3083 participants; high-certainty evidence). Subgroup analyses showed no evidence of differences in DFS according to BRCA mutation status, HRD status, lymph node status, or whether the intervention arm contained anthracycline chemotherapy or not. Platinum chemotherapy was associated with reduced dose intensity, with participants more likely to require chemotherapy delays (RR 2.23, 95% CI 1.70 to 2.94; 4 studies, 5 treatment comparisons, 1053 participants; moderate-certainty evidence), dose reductions (RR 1.77, 95% CI 1.56 to 2.02; 7 studies, 8 treatment comparisons, 2055 participants; moderate-certainty evidence) and early cessation of treatment (RR 1.20, 95% CI 1.04 to 1.38; 16 studies, 17 treatment comparisons, 4178 participants; moderate-certainty evidence). Increased haematological toxicity occurred in the platinum group who were more likely to experience grade III/IV neutropenia (RR 1.53, 95% CI 1.43 to 1.63; 19 studies, 20 treatment comparisons, 4849 participants; moderate-certainty evidence), anaemia (RR 8.20, 95% CI 5.66 to 11.89; 18 studies, 19 treatment comparisons, 4757 participants; moderate-certainty evidence) and thrombocytopenia (RR 7.59, 95% CI 5.10 to 11.29; 18 studies, 19 treatment comparisons, 4731 participants; moderate-certainty evidence). There was no evidence of a difference between chemotherapy groups in febrile neutropenia (RR 1.16, 95% CI 0.89 to 1.49; 11 studies, 3771 participants; moderate-certainty evidence). Renal impairment was very rare (0.4%, 2 events in 463 participants; note 3 studies reported 0 events in both arms; 4 studies; high-certainty evidence). Treatment-related death was very rare (0.2%, 7 events in 3176 participants and similar across treatment groups; RR 0.58, 95% 0.14 to 2.33; 10 studies, 11 treatment comparisons; note 8 studies reported treatment-related deaths but recorded 0 events in both groups. Thus, the RR and CIs were calculated from 3 studies rather than 11; 3176 participants; high-certainty evidence). Five studies collected quality of life data but did not report them.

AUTHORS' CONCLUSIONS

Platinum-based chemotherapy using carboplatin in the adjuvant or neoadjuvant setting improves long-term outcomes of DFS and OS in early TNBC, with no evidence of differences by subgroup. This was at the cost of more frequent chemotherapy delays and dose reductions, and greater haematological toxicity, though serious adverse events including neuropathy, febrile neutropenia or treatment-related death were not increased. These findings support the use of platinum-based chemotherapy for people with early TNBC. The optimal dose and regimen are not defined by this analysis, but there is a suggestion that similar relative benefits result from the addition of carboplatin to either anthracycline-free regimens or those containing anthracycline agents.

Abstract P4-06-01: Platinum-based chemotherapy for early triple-negative breast cancer: A Cochrane systematic review and meta-analysis

In early triple-negative breast cancer (eTNBC), platinum-based chemotherapy has been shown to improve pathological complete response, but recommendations to include platinum chemotherapy are not consistent in international guidelines. We performed a systematic review of published randomized control trials to assess to assess survival outcomes and quality of life for people with early TNBC. The results presented in this abstract have not yet been peer-reviewed by Cochrane. If the final version of the review meets the necessary standards, the review is expected to be published in the Cochrane Database of Systematic Reviews. Methods: Randomized controlled trials examining neoadjuvant or adjuvant platinum chemotherapy for eTNBC were included. We searched for published and unpublished data using standard Cochrane search strategies. The primary outcomes assessed were disease free survival (DFS) and overall survival (OS). Secondary outcomes included rate of pathological complete response (pCR), dose intensity and completion of regimens, grade III or IV toxicity related to chemotherapy, and quality of life. Prespecified subgroups included BRCA mutation status, HRD status, lymph node status, frequency of chemotherapy, type of platinum agent used, and the presence or absence of anthracycline chemotherapy. Results: From 3972 records, 19 published studies were eligible. Twenty six ongoing studies were identified. Risk of bias was judged low for most trials. There were 14 neoadjuvant chemotherapy trials, 4 adjuvant chemotherapy trials, and one trial of neoadjuvant and adjuvant therapy. Most trials used carboplatin (16 trials) followed by cisplatin (2), and lobaplatin (1). Eight trials had an anthracycline free intervention arm, 5 of which had a carboplatin-taxane intervention compared to an anthracycline-taxane control. All studies reporting DFS and OS used carboplatin. Twelve of 19 studies with a total of 3347 participants reported DFS data. Inclusion of platinum chemotherapy improved DFS in neoadjuvant and adjuvant setting (HR 0.63, 95% confidence interval (CI) 0.53-0.75; HR 0.69, 95% CI 0.54-0.88 respectively)). Eleven studies collected OS data, with a total of 3229 participants and 460 deaths reported. Inclusion of platinum chemotherapy in the regimen improved OS (neoadjuvant: HR 0.69, 95% CI 0.69, 0.55-0.86; adjuvant: 0.70, 95% CI 0.50 to 0.96). Median follow up for survival outcomes ranged from 36 – 97.6 months. Our analysis confirmed platinum chemotherapy increased pCR rates (RR 1.46 [1.33-1.61], p< 0.00001). Subgroup analysis revealed that survival outcome benefits were seen regardless of BRCA mutation status, HRD status, lymph node status, or whether the intervention arm contained anthracycline chemotherapy or not. Platinum chemotherapy was associated with reduced dose intensity, with participants more likely to require chemotherapy delays (RR 2.23 [1.70-2.94], 4 studies), dose reductions (RR 1.77 [1.56-2.02], 6 studies) and early cessation of treatment (RR 1.20 [1.04-1.38], 16 studies). Increased hematological toxicity occurred in the platinum group who were more likely to experience grade III/IV neutropenia (RR 1.55 [1.45-1.66]), anemia (RR 10.12 [6.61-15.50]) and thrombocytopenia (RR 7.59 [5.10-11.29]). There was no increase in febrile neutropenia (RR 1.16 [0.89-1.49]). Treatment-related death was very rare (7 events in 3094 patients) and similar across treatment groups (RR 0.58 [0.14-2.33]). Five studies collected quality of life data but did not report it. Conclusion: Platinum-based chemotherapy using carboplatin in the adjuvant or neoadjuvant setting improves long-term outcomes in eTNBC, regardless of the examined subgroups. This was at the cost of more frequent chemotherapy delays and dose reductions, and greater haematological toxicity. Benefit from platinum was seen both when platinum agents were added to anthracycline containing regimens, as well as in anthracycline-free regimens.

Citation Format: Sofia Mason, Melina Willson, Annabel Goodwin, Jane Beith, Sam J. Egger, Rachel F. Dear. Platinum-based chemotherapy for early triple-negative breast cancer: A Cochrane systematic review and meta-analysis [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P4-06-01.

Body weight management in overweight and obese breast cancer survivors

BACKGROUND

Studies suggest that overweight and obese breast cancer survivors are at increased risk of cancer recurrence and have higher all-cause mortality. Obesity has an impact on breast cancer survivor's quality of life (QOL) and increases the risk of longer-term morbidities such as type 2 diabetes mellitus and cardiovascular disease. Many cancer guidelines recommend survivors maintain a healthy weight but there is a lack of evidence regarding which weight loss method to recommend.

OBJECTIVES

To assess the effects of different body weight loss approaches in breast cancer survivors who are overweight or obese (body mass index (BMI) ≥ 25 kg/m²).

SEARCH METHODS

We carried out a search in the Cochrane Breast Cancer Group's (CBCG's) Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL, Issue 6), MEDLINE (2012 to June 2019), Embase (2015 to June 2019), the World Health Organisation International Clinical Trials Registry Platform (WHO ICTRP) and Clinicaltrials.gov on 17 June 2019. We also searched Mainland Chinese academic literature databases (CNKI), VIP, Wan Fang Data and SinoMed on 25 June 2019. We screened references in relevant manuscripts.

SELECTION CRITERIA

We included randomised controlled trials (RCTs), quasi-RCTs and randomised cross-over trials evaluating body weight management for overweight and obese breast cancer survivors (BMI ≥ 25 kg/m²). The aim of the intervention had to be weight loss.

DATA COLLECTION AND ANALYSIS

Two review authors independently performed data extraction and assessed risk of bias for the included studies, and applied the quality of the evidence using the GRADE approach. Dichotomous outcomes were analysed as proportions using the risk ratio (RR) as the measure of effect. Continuous data were analysed as means with the measure of effect being expressed as the mean differences (MDs) between treatment groups in change from baseline values with 95% confidence intervals (CIs), when all studies reported exactly the same outcomes on the same scale. If similar outcomes were reported on different scales the standardised mean difference (SMD) was used as the measure of effect. Quality of life data and relevant biomarkers were extracted where available.

MAIN RESULTS

We included a total of 20 studies (containing 23 intervention-comparisons) and analysed 2028 randomised women. Participants in the experimental groups received weight loss interventions using the core element of dietary changes, either in isolation or in combination with other core elements such as 'diet and exercise', 'diet and psychosocial support' or 'diet, exercise and psychosocial support'. Participants in the controls groups either received usual care, written materials or placebo, or wait-list controls. The duration of interventions ranged from 0.5 months to 24 months. The duration of follow-up ranged from three months to 36 months. There were no time-to-event data available for overall survival, breast cancer recurrence and disease-free survival. There was a relatively small amount of data available for breast cancer recurrence (281 participants from 4 intervention-comparisons with 14 recurrence events; RR 1.95, 95% CI 0.68 to 5.60; low-quality evidence) and the analysis was likely underpowered. Overall, we found low-quality evidence that weight loss interventions for overweight and obese breast cancer survivors resulted in a reduction in body weight (MD: -2.25 kg, 95% CI: -3.19 to -1.3 kg; 21 intervention-comparisons; 1751 women), body mass index (BMI) (MD: -1.08 kg/m², 95% CI: -1.61 to -0.56 kg/m²; 17 intervention-comparisons; 1353 women), and waist circumference (MD:-1.73 cm, 95% CI: -3.17 to -0.29 cm; 13 intervention-comparisons; 1193 women), and improved overall quality of life (SMD: 0.74; 95% CI: 0.20 to 1.29; 10 intervention-comparisons; 867 women). No increase was seen in adverse events for women in the intervention groups compared to controls (RR 0.94, 95% CI: 0.76 to 1.17; 4 intervention-comparisons; 394 women; high-quality evidence). Subgroup analyses revealed that decreases in body weight, BMI and waist circumference were present in women regardless of their ethnicity and menopausal status. Multimodal weight loss interventions (which referred to 'diet, exercise and psychosocial support') appeared to result in greater reductions in body weight (MD: -2.88 kg, 95% CI: -3.98 to -1.77 kg; 13 intervention-comparisons; 1526 participants), BMI (MD: -1.44 kg/m², 95% CI: -2.16 to -0.72 kg/m²; 11 studies; 1187 participants) and waist circumference (MD:-1.66 cm, 95% CI: -3.49 to -0.16 cm; 8 intervention-comparisons; 1021 participants) compared to dietary change alone, however the evidence was low quality.

AUTHORS' CONCLUSIONS

Weight loss interventions, particularly multimodal interventions (incorporating diet, exercise and psychosocial support), in overweight or obese breast cancer survivors appear to result in decreases in body weight, BMI and waist circumference and improvement in overall quality of life. There was no increase in adverse events. There is a lack of data to determine the impact of weight loss interventions on survival or breast cancer recurrence. This review is based on studies with marked heterogeneity regarding weight loss interventions. Due to the methods used in included studies, there was a high risk of bias regarding blinding of participants and assessors. Further research is required to determine the optimal weight loss intervention and assess the impact of weight loss on survival outcomes. Long-term follow-up in weight loss intervention studies is required to determine if weight changes are sustained beyond the intervention periods.

Platinum-containing regimens for triple-negative metastatic breast cancer

BACKGROUND

In a previous Cochrane Review, we found that for women with metastatic breast cancer unselected for triple-negative disease, there is little or no survival benefit and excess toxicity from platinum-based regimens. In subgroup analyses, however, we found preliminary low-quality evidence of a survival benefit from platinum-based regimens for women with metastatic triple-negative breast cancer (mTNBC). This review updates the evidence from the mTNBC subgroup analyses in the previous Cochrane Review.

OBJECTIVES

To assess the effects of platinum-containing chemotherapy regimens with regimens not containing platinum in the management of women with mTNBC.

SEARCH METHODS

We obtained relevant studies published prior to 2015 and their extracted results from the mTNBC subgroup analysis in the previous Cochrane Review. We searched the Cochrane Breast Cancer Group's Specialised Register, CENTRAL, MEDLINE, Embase, the World Health Organization's International Clinical Trials Registry Platform and ClinicalTrials.gov between 2015 and 27 September 2019. We identified further potentially relevant studies from previous trial reports, systematic reviews, and meta-analyses.

SELECTION CRITERIA

Randomised trials comparing platinum-containing chemotherapy regimens with regimens not containing platinum in women with mTNBC. Individual trials could compare one or more platinum-based regimens to one or more non-platinum regimens; hence there could be more 'treatment-comparisons' (i.e. platinum regimen versus non-platinum regimen comparison) than trials. Trial participants may have been purposely selected for mTNBC or inadvertently selected as a subgroup.

DATA COLLECTION AND ANALYSIS

At least two independent reviewers assessed studies for eligibility and quality, and extracted all relevant data from each study. We derived hazard ratios (HRs) for time-to-event outcomes, where possible, and used fixed-effect models for meta-analyses. We analysed objective tumour response rates (OTRRs) and toxicities as binary (dichotomous) outcomes with risk ratios (RRs) used as measures of effects. We extracted quality of life data, if available. We used GRADE to rate the quality of evidence for time-to-event and tumour response outcomes.

MAIN RESULTS

This review includes 13 treatment-comparisons involving 1349 women from 10 studies. Twelve of the 13 treatment-comparisons were included in one or more meta-analyses. Of the 13 treatment-comparisons, six and eight had published or provided time-to-event data on overall survival (OS) or progression-free survival/time to progression (PFS/TTP), respectively, that could be included in meta-analyses. Ten treatment-comparisons published or provided OTRR data that could be included in meta-analyses. Eight of the 13 treatment-comparisons were from studies that selected participants on the basis of mTNBC status, while the other five treatment-comparisons were from studies that reported mTNBC results as part of subgroup analyses. Analysis of six treatment-comparisons indicated that platinum-containing regimens may have provided a small survival benefit to mTNBC patients (HR 0.85, 95% CI 0.73 to 1.00; 958 women; moderate-quality evidence) with no evidence of heterogeneity (P = 0.41; I2 = 1%). Data from eight treatment-comparisons showed that platinum regimens may improve PFS/TTP (HR 0.77, 95% CI 0.68 to 0.88; 1077 women; very low-quality evidence). There was marked evidence of heterogeneity (P < 0.0001; I2 = 80%). There was also low-quality evidence of better tumour response for platinum recipients (RR 1.40, 95% CI 1.22 to 1.59; 1205 women) with some evidence of heterogeneity (P = 0.01; I2 = 58%). The observed heterogeneity for the PFS/TTP and OTRR outcomes may reflect between-study differences and general difficulties in assessing tumour response, as well as the varying potencies of the comparators. Compared with women receiving non-platinum regimens: rates of grade 3 and 4 nausea/vomiting were higher for platinum recipients (RR 4.77, 95% CI 1.93 to 11.81; 655 women; low-quality evidence) and rates of grade 3 and 4 anaemia were higher for platinum recipients (RR 3.80, 95% CI 2.25 to 6.42; 843 women; low-quality evidence). In general, however, relatively few intervention-comparisons could be included in meta-analyses for adverse events. None of the studies reported quality of life.

AUTHORS' CONCLUSIONS

For women with mTNBC, there was moderate-quality evidence of a small survival benefit from platinum-based regimens compared to non-platinum regimens. This finding is consistent with findings of a PFS/TTP benefit and improved tumour response from platinum-based regimens. These potential benefits, however, should be weighed against previously identified excess toxicities from platinum-based regimens, particularly regimens containing cisplatin. Further randomised trials of platinum-based regimens among women with mTNBC are required.

Platinum-containing regimens for metastatic breast cancer

BACKGROUND

Studies have reported high tumour response rates for platinum-containing regimens in the treatment of women with metastatic breast cancer. Most of these studies were conducted prior to the 'intrinsic subtype' era, and did not specifically focus on metastatic triple-negative breast cancers (mTNBCs).

OBJECTIVES

To identify and review the evidence from randomised trials comparing platinum-containing chemotherapy regimens with regimens not containing platinum in the management of women with metastatic breast cancer.

SEARCH METHODS

For this review update, we searched the Cochrane Breast Cancer Group's Specialised Register, CENTRAL, MEDLINE, Embase, the World Health Organization's International Clinical Trials Registry Platform and ClinicalTrials.gov on 28 May 2015. We identified further potentially relevant studies from handsearching references of previous trials, systematic reviews, and meta-analyses. Prior to this review update, the most recent search for studies was conducted in May 2003 for the original 2004 review.

SELECTION CRITERIA

Randomised trials comparing platinum-containing chemotherapy regimens with regimens not containing platinum in women with metastatic breast cancer.

DATA COLLECTION AND ANALYSIS

At least two independent reviewers assessed studies for eligibility and quality, and extracted all relevant data from each study. Hazard ratios (HRs) were derived for time-to-event outcomes, where possible, and fixed-effect models were used for meta-analyses. Objective tumour response rates (OTRRs) and toxicities were analysed as binary (dichotomous) outcomes with risk ratios (RRs) used as measures of effects. Quality of life data were extracted where available. GRADE was used to rate the quality of evidence for survival and tumour response outcomes at the level of subgroups selected and unselected for mTNBC, and for toxicity outcomes based on combining data from selected and unselected populations.

MAIN RESULTS

This update includes 15 new eligible treatment-comparisons from 12 studies. In total, 28 treatment-comparisons, involving 4418 women, from 24 studies are now included in one or more meta-analyses. Of the 28 treatment-comparisons, 19 and 16 had published or provided extractable time-to-event data on overall survival (OS) or progression-free survival/time to progression (PFS/TTP), respectively. All 28 treatment-comparisons provided OTRR data that could be included in meta-analyses. Most women recruited to the studies were not selected on the basis of mTNBC status.In a subgroup of three treatment-comparisons assessing women with mTNBC, platinum-containing regimens may have provided a survival benefit (HR 0.75, 95% CI 0.57 to 1.00; low-quality evidence). In women unselected for intrinsic subtypes such as mTNBC, there was little or no effect on survival (HR 1.01, 95% CI 0.92 to 1.12; high-quality evidence). This effect was similar to the combined analysis of survival data for both populations (HR 0.98, 95% CI 0.89 to 1.07; I² =39%, 1868 deaths, 2922 women; 19 trials). The difference in treatment effects between mTNBC women compared with unselected women was of borderline statistical significance (P = 0.05).Data from three treatment-comparisons with mTNBC participants showed that platinum regimens may improve PFS/TTP (HR 0.59, 95% CI 0.49 to 0.72; low-quality evidence). Thirteen treatment-comparisons of unselected metastatic participants showed that there was probably a small PFS/TTP benefit for platinum recipients, although the confidence interval included no difference (HR 0.92, 95% CI 0.84 to 1.01; moderate-quality evidence). Combined analysis of data from an estimated 1772 women who progressed or died out of 2136 women selected or unselected for mTNBC indicated that platinum-containing regimens improved PFS/TTP (HR 0.85, 95% CI 0.78 to 0.93). There was marked evidence of heterogeneity (P = 0.0004; I² = 63%). The larger treatment benefit in mTNBC women compared with unselected women was statistically significant (P < 0.0001).There was low-quality evidence of better tumour response in both subgroups of women with mTNBC and unselected women (RR 1.33, 95% CI 1.13 to 1.56; RR 1.11, 95% CI 1.04 to 1.19, respectively). Combined analysis of both populations was closer to the effect in unselected women (RR 1.15, 95% CI 1.08 to 1.22; 4130 women). There was considerable evidence of heterogeneity (P < 0.0001; I² = 64%), which may reflect between-study differences and general difficulties in assessing response, as well as the varying potencies of the comparators.Compared with women receiving non-platinum regimens: rates of grade 3 and 4 nausea/vomiting were probably higher among women receiving cisplatin- (RR 2.65, 95% CI 2.10 to 3.34; 1731 women; moderate-quality evidence) but the effect from carboplatin-containing regimens was less certain (RR 0.77, 95% CI 0.47 to 1.26; 1441 women; moderate-quality evidence); rates of grade 3 and 4 anaemia were higher among women receiving cisplatin- (RR 3.72, 95% CI 2.36 to 5.88; 1644 women; high-quality evidence) and carboplatin-containing regimens (RR 1.72, 95% CI 1.10 to 2.70; 1441 women; high-quality evidence); rates of grade 3 and 4 hair loss (RR 1.41, 95% CI 1.26 to 1.58; 1452 women; high-quality evidence) and leukopenia (RR 1.38, 95% CI 1.21 to 1.57; 3176 women; moderate-quality evidence) were higher among women receiving platinum-containing regimens (regardless of platinum agent).

AUTHORS' CONCLUSIONS

In women with metastatic breast cancer who do not have triple-negative disease, there is high-quality evidence of little or no survival benefit and excess toxicity from platinum-based regimens. There is preliminary low-quality evidence of a moderate survival benefit from platinum-based regimens for women with mTNBC. Further randomised trials of platinum-based regimens in this subpopulation of women with metastatic breast cancer are required.