If a woman is left waiting for radiotherapy after breast cancer surgery, there is a higher chance that the disease will come back, according to a new study.
The authors from the United States, Canada and Japan suggest that starting radiotherapy as soon as possible can minimise this risk.
Four to six weeks is generally accepted as a reasonable interval between cancer surgery and radiotherapy, but evidence on the effect of waiting times in patients with breast cancer is mixed.
So, the researchers studied the relation between interval to radiotherapy and recurrence of breast cancer.
They analysed national cancer records for 18,050 US women who were diagnosed with early stage breast cancer during 1991-2002 when they were aged 65 or older. All women received breast conserving surgery and radiotherapy, but not chemotherapy.
Demographic information was identified using data from the 2000 US population census, and women were followed up for an average of five years.
The results showed that starting radiotherapy more than six weeks after surgery was associated with a modest but significant increase in local recurrence.
More than one in four women in the study started radiotherapy after this time and 734 experienced a local recurrence at five years.
Further analysis showed a continuous relation between time to radiotherapy and local recurrence, suggesting that initiating radiation therapy as soon as possible could minimise local recurrence risk.
The study has been published on bmj.com.