The longer women wait for radiotherapy after breast cancer surgery, the more chance there is of local recurrence. 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. 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 radiotherapy after this time and some 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 minimize local recurrence risk. The cost of increasing capacity to ensure uniformly short waiting times could be substantial and would need to be weighed against the small absolute benefit in local recurrence, they add. But, given the known negative impact of local recurrence on overall survival, and the large numbers of women treated with radiotherapy for breast cancer, it seems appropriate to consider whether this is a price we should be prepared to pay. Minimizing delay improves outcomes, so investment and planning are needed.