How does first diagnosis of breast cancer compare with recurrent breast cancer?

This paper compared patients with new and patients with recurrent HER2 positive metastatic breast cancer. 

Improvements in breast screenings is associated with decreased recurrence (return) of breast cancer. This might increase the proportion of patients who have de novo breast cancer (first occurrence of cancer).

The human epidermal growth factor receptor 2 (HER2; a protein) is believed to be present in abnormally high levels in 15-20% of breast cancer patients. While in the past HER2 positivity (the presence of the protein) was associated with worse outcomes, since the introduction of trastuzumab (Herceptin; a drug that targets HER2) the outcome for HER2 positive patients has markedly improved.  As treatments continue to improve, it is important to understand the natural history of patients with de novo or recurrent HER2 positive cancer in a real-world setting.

The authors aimed to describe and compare patients with de novo and recurrent HER2 positive breast cancer.

1,021 patients with metastatic breast cancer (cancer that has spread to other regions in the body) that were HER2 positive were analyzed. 33% of patients had de novo breast cancer while 67% of patients had recurrent breast cancer. Patients with more than 4 metastatic cancer sites were more likely to have de novo breast cancer.

Treatment patterns were compared between de novo and recurrent patients. The proportion of patients who received trastuzumab plus chemotherapy was 59% in both groups. 22.9% of de novo cancer patients and 13.8% of recurrent cancer patients were treated with both chemotherapy and hormonal therapy. 2.4% of patients with de novo cancer and 9.2% of patients with recurrent cancer were treated with trastuzumab alone.

The average progression-free survival (time between diagnosis and disease progression) for patients with de novo breast cancer was 12.1 months compared to 9.3 months in recurrent breast cancer. The average overall survival (time from diagnosis to death) was 41.7 months for patients with de novo and 32.8 months for patients with recurrent breast cancer.

The risk of disease progression was 28% lower in patients with de novo cancer compared to recurrent cancer. The risk of death was 23% lower in patients with de novo cancer compared to recurrent cancer.

The differences in outcomes were suggested to be because recurrent cancer patients had already received previous treatment. 

The authors concluded that despite presenting with more advanced cancer, patients with de novo HER2 positive metastatic breast cancer had improved outcomes compared to patients with recurrent HER2 positive breast cancer. 

There were limitations to how patients were classified as de novo and recurrent disease that could affect results.