1. From your perspective as a medical oncologist, how has the treatment of breast cancer changed in recent years?
R.B.: Breast cancer is probably one of the cancer types in which predictive biomarkers and targeted therapies were implemented earliest, for example antihormonal treatments in hormone receptor-positive disease or anti-HER2 agents in HER2-positive breast cancer. The speed at which the field continues to evolve is impressive, with further refinement of breast cancer subtypes, the introduction of new targeted therapies and the identification of new predictive biomarkers.
In early breast cancer, we now have better tools to personalise systemic therapy, with a clear trend towards de-escalating chemotherapy where possible. This means using chemotherapy only when the tumour biology indicates a higher risk of relapse. On the other hand, for patients with a relevant risk of relapse, treatment can be escalated with therapies such as CDK4/6 inhibitors and novel agents targeting the estrogen receptor pathway.
A similar refinement and risk-adapted personalisation can be seen in surgery. Recent clinical trials have helped guide surgeons towards less extensive surgery of the axilla, thereby reducing the risk of lymphedema.
In advanced or metastatic breast cancer, new protein and genomic biomarkers are being used to stratify patients and as therapeutic targets for new small molecules and antibody-drug conjugates (ADCs). ADCs offer a more precise way of delivering chemotherapy to cancer cells.
Overall, we are becoming increasingly precise in determining which patient needs which therapy and when. However, there is still a long way to go. We need patients who are willing to participate in clinical trials to help develop the breast cancer therapies of tomorrow, while potentially gaining earlier access to new treatment options.
2. When deciding on the most appropriate treatment for an individual patient, what factors are most important today?
R.B.: An important nuance is that it is ultimately always the patient who decides on the most appropriate treatment. I see us oncologists as consultants who present the facts and therapeutic options, including the expected benefits and potential risks. Particularly in early breast cancer, we are often looking at relatively small gains in risk reduction, and we need to discuss these openly with the patient.
For example, a 5% survival benefit after five years may be enough for one patient to choose a treatment, whereas another patient may feel that this benefit does not justify undergoing risk-reducing therapy.
In general, our recommendations are made by an interdisciplinary tumour board involving surgeons, pathologists, radiation oncologists and medical oncologists. They are based on factors including the clinical stage - tumour size, lymph node involvement and distant metastases - how actively the cancer cells are dividing, the presence or absence of biomarkers, as well as the patient's age, comorbidities and overall condition.
Based on this recommendation, we then discuss the treatment strategy with the patient and their relatives.
3. Alongside your clinical work, you lead the Bill Lab at the Department of Biomedical Research (DBMR), where you study precision immuno-oncology. What questions from the clinic are you particularly trying to answer through your research?
R.B.: My research spans the entire spectrum, from basic questions aimed at understanding tumour biology to clinical questions. For example, we are investigating how an important process of cancer cell plasticity, known as epithelial-mesenchymal transition (EMT), shapes the immune cell compartment of tumours, using breast and head and neck cancers as model diseases.
This could help us better understand why certain tumours are resistant to immunotherapy and potentially reveal therapeutic targets that could sensitise tumours to drugs that boost the immune system. We are also working to decipher mechanisms of resistance to a newer class of drugs known as antibody-drug conjugates.
In addition, we are strongly committed to answering clinically relevant questions using retrospective data. For example, we are investigating how well metaplastic breast cancer - a rare and aggressive subtype - responds to chemo-immunotherapy. In collaboration with the Swiss Cancer Institute (SCI), we are also working on exciting clinical projects in breast cancer, including a clinical trial - stay tuned.
