A more and more personalized treatment needs specific drugs and tests able to understand which therapy is the most suitable. For example, among patients with early stage HER2 positive cancer who underwent therapy before surgery it is now possible to identify those who are at greater risk of relapse and therefore direct them towards a more effective therapy, trastuzumab emtansine (TDM- 1). Like? Thanks to an examination conducted by the anatomopathologist, the evaluation of the pathological complete response (pCR). A new turning point in the path of these patients that must be managed within the interdisciplinary team that follows it, of which the pathologist is one of the cornerstones. As explained by Caterina Marchiò, Associate Professor in Pathological Anatomy FPO-IRCCS Candiolo, Department of Medical Sciences of the University of Turin.
What is the role of the pathologist today in the pathway of patients with HER2 positive breast tumors?
“The pathologist has an important role in two essential moments of the diagnostic-therapeutic process: in the diagnosis phase, to know what type of breast cancer we are facing, and after neoadjuvant therapy, to understand if the disease has responded or less to the molecular targeted treatment administered. Before the surgery we analyze the biopsies from the histological point of view, while after we have all the tissue removed by the surgeon at our disposal “.
What is pathological complete response (pCR) and how important is it to recognize it correctly?
“When we analyze the tissue taken during the surgery we are faced with three possibilities. In the first – which we hope – all the tumor cells have disappeared and what we see is the so-called empty tumor bed, formed only by fibrous tissue, which is like a sort of scar: it means that the tumor has responded optimally to neoadjuvant therapy. . This situation is called Pathological Complete Response and means that there is no residual disease. As you can imagine, we must be sure that not a single cancer cell is left, because the patient’s future path depends on the result of our analysis. The second possibility is that the tumor has not responded to therapy at all: it is still present and has not shrunk significantly. This means that the disease is likely to be resistant ab initio to drugs that have been administered in the neoadjuvant phase and that from now on it will have to continue with different drugs. The third possibility is the middle way: there is still residual disease, but the tumor has, in part, responded to the treatment. Also in this case the treatment will continue with different drugs than those used in the neoadjuvant phase “.
In this intermediate situation, what is your task?
“We must communicate to the oncologist how much the disease has responded. In medical jargon, we say that the answer must be ‘graded’: it makes a difference whether there is still a lot of residual tumor or if it is minimal. Sometimes we are faced with a tumor that has not really reacted, while other cases are approaching the complete pathological response and the prognosis is much more favorable. They are essential information for the oncologist, to establish the best therapeutic strategy for that patient. In cases where the tumor is still present, it is also essential to analyze the resection margins, to ensure the surgeon that there are no cancerous cells. If not, it is necessary to widen the margins ”.
How important is multidisciplinarity?
“It is essential. Our work would not exist without that of other colleagues and vice versa. It is true that the patient always sees only the oncologist or the surgeon: ours is a work behind the scenes, which however has really important implications, because it allows us to determine what to do to best treat the patient “.
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