Preliminary Analysis of Radiotherapy Data from CALGB 9082: Variability of Treatment Fields for Local/Regional Breast Cancer and the Impact of High Dose Chemotherapy on the Ability to Deliver Radiation Therapy

Theodore Robnett, MD
OncoLink Assistant Editor
Last Modified: November 2, 1999

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Presenter: Lawrence B. Marks, M.D.
Affiliation: Duke University/CALGB/SWOG

Summary:
Positive contributions of radiotherapy (RT) and chemotherapy in patients with high-risk breast cancer are well documented, but the sequencing of these modalities and dosage of chemotherapy in such patients remains controversial. This offering examines the effect of high dose chemotherapy followed by bone marrow transplant (HD) versus intermediate dose (ID) pre-radiation chemotherapy on the likelihood that patients receiving such treatment will go on to actually receive RT.

Methods:
The chance that patients would receive any RT, have modifications to RT, and complete RT were examined. As an independent point, the study also documents deviation of delivered RT fields from protocol specifications.

Results:

  • There was a statistically significant difference in all of the examined RT-related treatment aspects when compared between HD and ID chemotherapy, with patients in the HD arm being more likely to have compromise of RT.
  • In the HD arm, only 82% of patients initiated RT compared with 92% of patients in the ID arm (p < 0.001).
  • Once started on RT, 29% of patients in the HD arm required some modification of treatment, compared with 14% in the ID arm (p < 0.001), and 9% of patients did not complete their planned treatment, compared with 2% in the ID arm (p < 0.001).
  • In examining the treated fields, 14% of treatment plans failed to place a hanging block when rotating the collimator on tangent fields, 4% placed an inferior supraclavicular block (causing a likely cold spot), and 14% placed a match line within 15 mm of the inferior humoral head (including essentially the full axilla in the field).

Clinical/Scientific Implications:

  • The patient treatment outcome data from this study, which were presented at ASCO earlier this year, showed no difference between the ID and HD arms.
  • Taking these data into account and considering the data presented in this paper, it seems plausible to conclude that HD chemotherapy jeopardizes the chance that patients will receive adequate RT, which has been proven to be of benefit in this population in other studies.
  • This information should be heavily considered in future decisions regarding sequencing of treatment for high risk breast cancer patients.

ASTRO coverage is sponsored, in part, by Varian Medical Systems, Inc.


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