Complete remission in metastatic breast cancer: expecting the unexpected. Results of a cross-sectional study – Beyond the abstract.

Metastatic breast cancer patients’ prognosis has significantly improved in last decades, thanks to the advent of new therapeutic compounds.(1) Nonetheless metastatic breast cancer is still considered an incurable condition, as complete remissions are rare.(2) Scarcity of data exists in literature about tumor-or patient-related factors potentially associated with this outcome. Moreover long-term prognosis of this patients’ subset is unclear, although some cases of apparent cure have been described.(3)

The present work is a cross-sectional cohort study aimed at analyzing the phenomenon of breast cancer complete remission in a homogeneous population of patients, treated within the same Institution and followed-up for at least two years.(4) We performed a cross-sectional analysis of all metastatic breast cancer patients treated at Istituto Nazionale dei Tumori, Milan, Italy, between April 2012 and April 2013. All cases obtaining complete response after any lines of systemic treatment were selected for analysis and their characteristics were collected from Institutional database.

We selected 76 patients, with a median age of 56 years. The most common sites of disease at the time of complete response were skin and lymph nodes (56.6%), bone (34.2%), liver (25.0%), lung (14.5%) and CNS (2.6%). 116 complete remissions were analyzed, as 30 patients (39.5%) achieved this result more than once. Complete response was obtained as a consequence of first, second, third, fourth and sixth line of treatment in 32.8%, 44.0%, 16.4%, 5.2% and 1.7% of cases respectively. In 53.4% of cases maintenance treatment was administered, with endocrine or anti-HER2 therapies. At the time of dataset lock, 60.9% were alive and disease-free, 34.8% were alive with metastatic disease, 4.3% had died and 9.2% had been lost at follow-up. The most common sites of progression were bone and soft tissues (31.6% each).

Our results supports the opportunity of proposing active treatments to breast cancer patients beyond first and second lines. Indeed, the evidence that complete response could be obtained even in advanced settings should be kept in mind whenever planning a long term therapeutic strategy for these women.(5)

Secondarily, more than 50% of complete responses were obtained during maintenance therapies. Notably, only 50.7% of these cases had already achieved CR during induction therapy, while the others obtained CR after a partial response or even a stable disease at the end of the previous line. This observation underlines the importance of maintenance therapy, as it appears not only to stabilize the previously achieved results but also to improve therapeutic outcomes.(6)

The last issue suggested by our study concerns the role of local treatments. Oncologists’ attitude is becoming more and more interventional especially in oligometastatic disease, defined as the presence of one or few metastatic lesions usually within a single organ. Our work supports this trend of clinical practice, showing that a considerable subgroup of patients may succeed in obtaining durable CRs after combinatory local and systemic approaches.(7)

In conclusion, our paper supports the potential “curability” of a subset of MBC patients. Additional studies are needed to shed a light on the role of combinatory strategies potentially needed to gain this result.

Written by: Giulia Galli, MD

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2. Deker DA, Ahmann DL, Bisel HF, et al. Complete responders to chemotherapy in metastatic breast cancer: characterization and analysis. JAMA 1979; 242(19):2075-2079

3. Pedrazzini A, Cavalli F, Brunner KW, et al. Complete remission following endocrine or combined cytotoxic and hormonal treatment in advanced breast cancer. A retrospective analysis. Oncol 1987; 44(1):51.

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