Progress in breast cancer—can we do better?


Progress in breast cancer—can we do better?

S.F. Dent, MD*


Breast cancer remains the most common malignancy diagnosed in women in North America. In 2017, 26,300 women and 230 men were diagnosed with breast cancer in Canada, and 5000 women and 43 men died of the disease1. For individuals with early-stage breast cancer, the last few decades have witnessed the evolution of systemic therapy from cyclophosphamide–methotrexate–fluorouracil to anthracycline–taxane combinations, with “real” gains in overall survival2. Individuals diagnosed with advanced breast cancer are living longer because of the introduction of novel cancer therapies3. Since the peak in the cancer mortality rate in Canada in 1988, estimates suggest that 32,082 breast cancer deaths have been avoided as a result of cancer prevention and treatment strategies1—but can we do better?

Current algorithms for the treatment of early and advanced breast cancer are based on a knowledge of signalling pathways, the interconnections in those pathways, and the importance of receptors and biomarkers. Endocrine therapy remains the mainstay of treatment for individuals with estrogen-sensitive early breast cancer, but the “optimal” duration of therapy remains unclear (5 vs. 7 vs. 10 years). Significant advances have been made in the treatment of estrogen-sensitive advanced breast cancer with the introduction of targeted agents such as mtor (mechanistic target of rapamycin) inhibitors (for example, everolimus)4 and, more recently, cyclin-dependent kinase 4/6 inhibitors given in combination with endocrine therapy5. However, research is still needed to improve the understanding of why individuals who initially respond to that approach develop resistant disease. For individuals with her2-positive disease, her2-targeted agents such as trastuzumab and pertuzumab have significantly improved clinical outcomes for individuals with early and advanced breast cancer6. However, at 10 years, an estimated 30% of individuals with early breast cancer treated with trastuzumab will relapse (hera study), and those who present with advanced disease will eventually develop resistance to the targeted approach7. Despite significant research efforts, few advances have been made in treatment options for individuals with triple-negative breast cancer (disease negative for estrogen receptor, progesterone receptor, and her2). For individuals with germline BRCA-mutated, her2-negative advanced breast cancer, the parp [poly (adp-ribose) polymerase] inhibitor olaparib (approved by Health Canada on 8 May 2018) has shown meaningful clinical benefit8. Clinical trials are currently exploring the potential role for immunotherapy in the treatment of triple-negative breast cancer, but clearly, more research is needed to develop treatment strategies for that patient population.

In this special issue of Current Oncology, contributors discuss current recommendations for breast screening to optimize early detection of breast cancer, as well as the utility of genomic assays in clinical decision-making for individuals with early-stage disease. Current treatment options for endocrine-sensitive advanced breast cancer are presented, as is an overview of mechanisms of resistance and ongoing clinical trials exploring novel agents that could be combined with endocrine therapy. Contributors review the strengths and weaknesses of clinical practice guidelines from various professional organizations and consensus groups with respect to their methodologic quality, recommendations, and implementability. Biosimilar agents are rapidly being developed, with the goal of offering cost-effective alternatives to biologics. In this issue, contributors discuss the evolution of biosimilars in oncology with a focus on trastuzumab. Given the rising costs of cancer therapies, interest in determining the “added value” of novel treatment options is increasing. In this issue, contributors present a value assessment analysis of drugs funded between 2012 and 2017 for advanced breast cancer in Canada. All of those efforts will undoubtedly lead to further improvement in clinical outcomes for individuals faced with a diagnosis of breast cancer. Yes, we can do better, and we will!


I have read and understood Current Oncology’s policy on disclosing conflicts of interest, and I declare the following interests: honoraria received from Novartis, Eli Lilly, Hoffman La–Roche, and Pfizer.


*The Ottawa Hospital Cancer Centre and University of Ottawa, Ottawa, ON.


1. Canadian Cancer Society’s Advisory Committee on Cancer Statistics. Canadian Cancer Statistics 2017. Toronto, ON: Canadian Cancer Society; 2017.

2. Early Breast Cancer Trialists’ Collaborative Group. Long-term outcomes for neoadjuvant versus adjuvant chemotherapy in early breast cancer: meta-analysis of individual patient data from ten randomised trials. Lancet Oncol 2018;19:27–39.
cross-ref  pmc  

3. Chia SK, Speers CH, D’yachkova Y, et al. The impact of new chemotherapeutic and hormone agents on survival in a population-based cohort of women with metastatic breast cancer. Cancer 2007;110:973–9.
cross-ref  pubmed  

4. Baselga J, Campone M, Piccart M, et al. Everolimus in post-menopausal hormone-receptor-positive advanced breast cancer. N Engl J Med 2012;366:520–9.

5. Sammons SL, Topping DL, Blackwell KL. hr+, her2–advanced breast cancer and cdk4/6 inhibitors: mode of action, clinical activity, and safety profiles. Curr Cancer Drug Targets 2017;17:637–49.
cross-ref  pmc  

6. Schramm A, De Gregorio N, Widschwendter P, Fink V, Huober J. Targeted therapies in her2-positive breast cancer—a systematic review. Breast Care (Basel) 2015;10:173–8.

7. Cameron D, Piccart-Gebhart MJ, Gelber RD, et al. on behalf of the Herceptin Adjuvant Trial study team. 11 Years’ follow-up of trastuzumab after adjuvant chemotherapy in her2-positive early breast cancer: final analysis of the Herceptin Adjuvant (hera) trial. Lancet 2017;389:1195–205.
cross-ref  pubmed  pmc  

8. Robson M, Im SA, Senkus E, et al. Olaparib for metastatic breast cancer in patients with a germline BRCA mutation. N Engl J Med 2017;377:523–33.
cross-ref  pubmed  

Correspondence to: Susan F. Dent, The Ottawa Hospital Cancer Centre, 501 Smyth Road, Ottawa, Ontario K1H 8L6. E-mail:

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Current Oncology, VOLUME 25, SUPPLEMENT 1, June 2018

Copyright © 2019 Multimed Inc.
ISSN: 1198-0052 (Print) ISSN: 1718-7729 (Online)