In the United States, 1 in 8 women develop breast cancer at some point in their lives.
A study analyzed data on 6,827 women, 19 to 85 years old, who had chemotherapy after surgery for stage 1,2, or 3 invasive breast cancer.
84% of the women in the study had stage 1 or 2 cancers.
40% of the women in the study started chemotherapy within 30 days of their surgery. 44% started chemotherapy within 31 to 60 days after surgery.
After 5 years 21% (1,437) of the women died, 31% (2,135) had the cancer reoccur and the cancer metastasized in 28% (1,924) of the women.
Women who waited the longest to start chemotherapy were 19 percent more likely to die within 5 years than those who started it within 30 days.
The study discovered that risks varied by the type and stage of cancer. Women with hormone-receptive positive tumors had a 29% greater chance of dying if they delayed chemotherapy for more than 60 days. Women with triple-negative breast cancer increased their risk by 54%. Women with stage 2 cancer who started chemotherapy after 60 days had a 20% greater rick of metastasis. Women with stage 3 cancer had a 36% greater chance if they waited more than 60 days to receive chemotherapy.
Women with more advanced and more aggressive types of cancer benefited the most from an early start of chemotherapy.
Chemotherapy is prescribed to kill any cancer cells remaining after surgery. The strong drugs used in chemotherapy decrease the chance that the cancer will recur or spread.
The study did not include women who did not have chemotherapy at all as part of their breast cancer treatment.