Harold J. Burstein, MD, PhD, Editor

But individualized care for breast cancer patients is not just a slogan; it is the current reality and represents the alignment of scientific discoveries with clinical practice. As we are in the age of tailored approaches to care, we have a whole new set of questions. Who is the tailor, and how good are they? Who picked out the cloth, and where was it made? When does the client show up to be measured? Who handles the alterations? Does the garment really fit better than one off the rack? And can we afford bespoke care?

For breast cancer patients expecting tailored treatment, those questions hold powerful resonance. The articles in this issue of Hematology/Oncology Clinics of North America seek to address these many questions.

Classifying the breast cancer is the first step in individualized care. As more of our treatment decisions hinge on the fundamental biology of the cancer, and not on the surgical or anatomical stage, the correct classification of the tumor is a sine qua non for appropriate therapy. This realization moves the pathologist to the center of the treatment team in breast cancer medicine. High-quality pathology and diagnostic testing are critical for correctly assigning tumors into the various treatment subsets. Rigorous pathology can still make for fraught clinical decisions; tumors are rarely homogeneous, and natural variations in “simple” things like histological grade, estrogen receptor status, and HER2 status still post vexing clinical challenges. But superb pathology, fully integrated into the multidisciplinary treatment team, is now essential for the best breast cancer care. As clinicians increasingly lean on molecular diagnostics to make treatment choices, the importance of quality control and careful attention to tumor biology will grow greater, and not diminish, in the pathology laboratory.

Our systemic treatment approaches are all driven by the underlying classification of the breast cancer. For estrogen-receptor-positive breast cancers, endocrine therapy remains the mainstay of treatment. For HER2-driven breast cancers, it is anti-HER2 therapy. Having a powerful target fuels successful drug discovery. New innovations in targeting ER and HER2 pathways have led to dramatic transformations in management of these tumor subsets in recent years and hold promise of more to come. Chemotherapy plays a role in many breast cancer types including triple-negative, HER2, and HER2 positive tumors. A particular challenge has been to ascertain reliably which ER-positive cancers can safely be treated without chemotherapy. Here again, the decisive piece of information lies within the tumor pathology, and the debate centers on how to most accurately classify tumors for treatment.

The reliance on tumor biology for choosing systemic therapies has altered the ways we think about integrating local and adjuvant therapy for breast cancer. One immediate consequence has been the opportunity to lessen the extent of surgery for breast cancer, and in particular, to avoid axillary dissection. Because the “die is cast” for treatment based on basic staging and tumor pathology, we no longer have to remove the full axillary node basin to justify the likely adjuvant therapies. The result is less morbidity for the patient, without any negative impact on treatment outcomes. Similarly, we can often employ neoadjuvant therapy based purely on tumor pathology––and not stage––as our initial treatment for breast cancer. But the use of neoadjuvant therapy poses new dilemmas, such as what to do when our initial therapy seems more––or less––successful than we had anticipated and hoped for. Can we respond to these dynamic interactions between tumor and treatment to individualize the care of the patient based on the actual treatment response, and if so, how?

But tailoring treatment based on tumor biology is not the full measure of individualized care for the breast cancer patient. Indeed, more than ever, it seems important to “put the person” back in personalized medicine. Not all breast cancer patients are the same people, even if they have the same kind of breast cancer. Individuals struggle with the physical, social, and psychological consequences of diagnosis and treatment and need support as cancer survivors. Older patients with breast cancer––the vast majority of all breast cancer patients––warrant special consideration because of real-world consequences of aging and comorbid conditions. Even when treatments work, there are tradeoffs between benefit and side effects. The fields of prevention and DCIS management are checkered by such tradeoffs and being able to frame the likely gains versus real pains are a critical part of caring for patients who are at risk for but have not yet developed breast cancer. Because of the generally good outcomes for such women, the calculation of treat versus not treat is especially difficult to add up, and personal preferences will matter a great deal when actually choosing treatments.

In an age of tailored approaches to breast cancer, it is tempting to think that the treatment plan for each individual will be different. But, of course, those plans are not. In fact, within the confines of breast cancer subtypes, rather clear treatment approaches are well-documented, and increasingly there is pressure to standardize our approaches. This of course is a paradox of the modern era in medicine––the pursuit of pathways-based treatments build on strong evidence, to achieve higher quality and efficiency while simultaneously appreciating the uniqueness of each patient and tumor. Not everyone needs a tailored suit; off the rack works pretty well for many, especially with a few alterations. Implementing guidelines that include both tailored and premeasured approaches is a key task for academic and community oncologists.

While everyone wants progress in breast cancer, there is growing concern that we cannot afford the progress we are making. Not everyone can afford a couture garment. What are the real costs of cancer care, and what is worth paying for? Defining those criteria is proving every bit as essential as defining breast cancer subsets. This issue, with its theme of individualized care for breast cancer, seeks to frame and discuss these many and varied meanings of personalized, tailored, and targeted treatment.