Patients with triple-negative breast cancer who delayed starting adjuvant chemotherapy for more than 30 days after surgery were at significantly higher risk for disease recurrence and death compared with those who started the treatment in the first 30 days after surgery, according to a retrospective study presented at the 2018 San Antonio Breast Cancer Symposium, held Dec. 4-8.
"For this study we included triple-negative breast cancer patients who underwent surgery as first treatment followed by chemotherapy and/or radiotherapy," said Zaida Morante, MD, a medical oncologist at Instituto Nacional de Enfermedades Neoplásicas in Lima, Peru. "Most guidelines recommend starting this adjuvant chemotherapy within four to six weeks after surgery for any type of breast cancer. Others recommend starting as soon as clinically possible within 31 days of surgery, however, the optimal time to initiate chemotherapy is unknown.
"We have seen in our clinical practice that for many reasons, there is often a delay in starting adjuvant chemotherapy for patients with triple-negative breast cancer," continued Morante. "We analyzed real-world data to determine whether these delays impact disease-free or overall survival for patients."
Morante and colleagues found that patients who delayed starting adjuvant chemotherapy for more than 30 days after surgery had a more than 90 percent increased risk for disease recurrence and death compared with those who started the treatment in the first 30 days after surgery. This risk is increased if the adjuvant treatment is given after 60 days.
"Our data show that it must be a priority for patients with triple-negative breast cancer to begin adjuvant chemotherapy within 30 days of completing surgery," said Morante. "After this period of time, the benefit of the chemotherapy is significantly diminished."
Morante and colleagues retrospectively analyzed data obtained from the medical records of 687 patients with stage 1-3 triple-negative breast cancer who had undergone surgery and went on to receive adjuvant chemotherapy in a public institution. The median follow-up was 101 months and the median time to starting adjuvant chemotherapy was 41 days; 189 patients started the treatment at or before 30 days, 329 started it from 31 to 60 days, 115 started it from 61 to 90 days, and 54 started it more than 90 days after surgery.
As the time to starting adjuvant chemotherapy increased, the 10-year disease-free survival rate decreased; it was 81.4 percent, 68.6 percent, 70.8 percent, and 68.1 percent among patients who started the treatment at or before 30 days after surgery, 31 to 60 days after surgery, 61 to 90 days after surgery, and more than 90 days after surgery, respectively. The 10-year overall survival rate also decreased as the time to starting adjuvant chemotherapy increased; it was 82 percent, 67.4 percent, 67.1 percent, and 65.1 percent for the four groups of patients, respectively.
The researchers then studied how the extent of delay in starting chemotherapy was associated with an increased risk for disease recurrence and death. They found that compared with patients who started adjuvant chemotherapy in the first 30 days after surgery, risk for disease recurrence was increased by 92 percent for those who delayed starting the treatment for 31 to 60 days after surgery, by 138 percent for those who delayed starting the treatment for 61 to 90 days after surgery, and by 147 percent for those who delayed starting the treatment for more than 90 days after surgery. The risk of death compared with patients who started adjuvant chemotherapy in the first 30 days after surgery increased by 94 percent, 145 percent, and 179 percent for the three groups, respectively.
According to Morante, the main limitation of the study is that it is a retrospective analysis of a single institution experience.
Morante declares no conflicts of interest.