Matching supraclavicular fields to the extent of axillary surgery in women prescribed radiotherapy for early stage carcinoma of the breast.
OBJECTIVE
To determine (1) if the lower border of a standard anterior radiotherapy field to the supraclavicular fossa matches the upper limit of level II/III axillary dissection; and (2) whether standard lung blocks in patients prescribed axillary radiotherapy shield target axillary tissue in women with breast cancer.


METHODS
Between 1999 and 2001, 30 women with breast cancer undergoing level II/III axillary dissection had titanium clips placed to define the upper and medial limits of surgery. At radiotherapy planning, a supraclavicular fossa field similar to that described in the UK START trial protocol was simulated, with head twist applied to position the inferior field border (50% isodose) 1 cm below and parallel to the lower border of the clavicle. The field position was recorded on X-ray film. The location of the most superior axillary clip was measured in relation to this inferior field border on the X-ray film. The location of the most medial clip was measured in relation to the lung/chest wall interface.


RESULTS
The median distance between the most superior clip and the inferior border of the supraclavicular field was 3.6 cm (0.8-6.9 cm), representing significant underlap in all cases. In addition, five out of 30 (17%) patients had surgical clips over 2.0 cm medial to the lung/chest wall interface, suggesting that medial lymph nodes in an undissected axilla would be shielded by standard lung blocks in patients prescribed axillary radiotherapy.


CONCLUSIONS
Current standard radiation fields to the supraclavicular fossa, as applied in this study, leave apical axillary lymph nodes untreated in a high proportion of patients. Standard lung shielding, as applied in this study to patients simulated for axillary radiotherapy, protect medial axillary lymph nodes in a few patients. A change in practice is recommended.
Wheatley
D
D
Department of Radiotherapy, The Royal Marsden Hospital, Sutton, Surrey, UK.
Adwani
A
A
Ebbs
S
S
Hanson
J
J
Ross
G
G
Sharma
A K
AK
Wells
P
P
Yarnold
J
J
D000328:Adult; D000368:Aged; D001365:Axilla; D001943:Breast Neoplasms / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D002968:Clavicle / Q000000981:diagnostic imaging; D019583:Dose Fractionation, Radiation; D005260:Female; D006801:Humans; D008168:Lung / Q000473:pathology / Q000528:radiation effects; D008197:Lymph Node Excision; D008875:Middle Aged; D009367:Neoplasm Staging; D010347:Patient Care Planning; D011832:Radiation Injuries / Q000517:prevention & control*; D013902:Radiography, Thoracic; D018714:Radiotherapy, Adjuvant / Q000379:methods*; D012680:Sensitivity and Specificity; D013525:Surgical Instruments