Trial Information

A Phase III Study of Adjuvant Radiation Therapy in Early Breast Cancer Comparing the Use of Breast Intensity Modulated Radiation Therapy (IMRT) to Conventional Wedge Technique

1. Description of the Problem:

The majority of breast cancer patients are treated with breast-conserving surgery
followed by radiotherapy, giving loco-regional control rates similar to mastectomy.
Currently, the "standard" breast radiotherapy technique includes treatment of the
entire breast with a tangential opposed pair of photon beams. The standard technique
leads to significant acute skin toxicity, ranging from breast erythema to moist
desquamation, in approximately 40% of patients. This toxicity may lead to interruptions
in treatment delivery; may increase the risk of developing late skin toxicity including
telangiectasia, skin fibrosis and chronic breast pain; and may also be associated with
a significant decrease in health-related quality of life (HRQOL). Published data from
dosimetric studies suggest that dose variations in excess of 10% within the breast may
be the most important predictor of acute radiation-induced skin toxicity (RR = 9.7),
and that dose toxicity occurs more frequently in the inframamary fold. A study
performed at TSRCC shows that intensity modulated radiotherapy (IMRT) allows for
significant improvements in dose homogeneity within the breast compared to standard
breast radiotherapy techniques. Furthermore, the hot spot over 10% seen in the
inframamary fold for patient with large breast volume is removed.

2. Objectives:

- To determine if the occurence of acute skin toxicity in women receiving adjuvant
breast radiation with IMRT is less frequent compared to women treated with
conventional technique.

- To determine if the HRQOL scores, and specifically breast module subscale scores,
in women receiving adjuvant breast radiation with IMRT is better than HRQOL scores
in women receiving conventional technique.

- To perform a comparison of costs in the delivery of breast radiotherapy using IMRT
to conventional technique.

- To determine if an increased acute skin toxicity translates into an increased late
skin toxicity.

3. Hypothesis:

We hypothesize that women receiving adjuvant breast radiation with IMRT will have
significantly less acute skin toxicity and improved HRQOL compared to women treated with
conventional techniques. We also hypothesize that there would not be increased cost related
to IMRT compared to conventional technique.

Research plan: A Phase III randomised controled trial is planned, with blocked
stratification on breast size and boost delivery. Eligible women include those who have been
referred to TSRCC following breast-conserving surgery. They will be randomized to receive
either a conventional technique treatment, either breast IMRT. Acute skin toxicity will be
assessed weekly during radiotherapy and up to one month following completion of radiotherapy
using the previously validated RTOG acute skin toxicity scale. The occurence, duration and
intensity of acute skin toxicity will be compared. HRQOL will be assessed during and after
irradiation, using validated EORTC instruments (EORTC QLQ-C30 and QLQ-BR23). 340 patients
will be accrued in order to detect a 15% reduction in the ocurence of acute skin toxicity
with IMRT using an a=0.05, b=0.80.