Waiting times for radiotherapy after breast-conserving surgery and the association with survival: a path analysis.

AIMS: To investigate the association between radiotherapy waiting times and survival in women who have undergone breast-conserving surgery using data from two English cancer registry regions. The data were analysed using path analysis to account for the complex variable interrelationships within the data.
MATERIALS AND METHODS: Cases of female invasive breast cancer diagnosed during the period 1 January 1998 to 31 December 2005 were identified and linked to an extract of Hospital Episode Statistics data. A subset of these linked records where women underwent breast-conserving surgery was extracted (n=18,158). Patient, tumour and treatment information were extracted. A path model was developed with three outcome variables: survival, time to receive radiotherapy and receipt of chemotherapy before radiotherapy.
RESULTS: During the study period, the median radiotherapy waiting time in region 1 increased from 70 days to 128.5 days. In region 2, the median wait increased from 44 days in 1998 to 68 days in 2001, then decreased to 42 days by 2005. In the path model, radiotherapy waiting time was not associated with survival (hazard ratio=1.00, 95% confidence interval 0.99-1.01 per week increase in both regions). Patients receiving chemotherapy before radiotherapy waited 12.3 weeks (region 1) and 6.3 weeks (region 2) longer for their radiotherapy than those not receiving chemotherapy. Patients with stage II/III disease waited longer than patients with stage I disease. Younger age, diagnosis of stage II/III disease and presence of co-morbidities were associated with increased odds of receiving chemotherapy before radiotherapy.
CONCLUSIONS: This study found no association between waiting times for radiotherapy and survival in two regions of England, despite increases in waiting times over the study period. Such an association, if real, may only become apparent after a longer period of follow-up.