Scapula alata in early breast cancer patients enrolled in a randomized clinical trial of post-surgery short-course image-guided radiotherapy

Abstract

Background: Scapula alata (SA) is a known complication of breast surgery associated with palsy of the serratus anterior, but it is seldom mentioned. We evaluated the risk factors associated with SA and the relationship of SA with ipsilateral shoulder/arm morbidity in a series of patients enrolled in a trial of post-surgery radiotherapy (RT).

Methods: The trial randomized women with completely resected stage I-II breast cancer to short-course image-guided RT, versus conventional RT. SA, arm volume and shoulder-arm mobility were measured prior to RT and at one to three months post-RT. Shoulder/arm morbidities were computed as a post-RT percentage change relative to pre-RT measurements.

Results: Of 119 evaluable patients, 13 (= 10.9%) had pre-RT SA. Age younger than 50 years old, a body mass index less than 25 kg/m2, and axillary lymph node dissection were significant risk factors, with odds ratios of 4.8 (P = 0.009), 6.1 (P = 0.016), and 6.1 (P = 0.005), respectively. Randomization group was not significant. At one to three months' post-RT, mean arm volume increased by 4.1% (P = 0.036) and abduction decreased by 8.6% (P = 0.046) among SA patients, but not among non-SA patients. SA resolved in eight, persisted in five, and appeared in one patient.

Conclusion: The relationship of SA with lower body mass index suggests that SA might have been underestimated in overweight patients. Despite apparent resolution of SA in most patients, pre-RT SA portended an increased risk of shoulder/arm morbidity. We argue that SA warrants further investigation. Incidentally, the observation of SA occurring after RT in one patient represents the second case of post-RT SA reported in the literature.

Trial registration: ClinicalTrials.gov NCT00459628.

Figures

Figure 1

Physical measurements. Measured at five locations (marked with a dermographic pencil but not visible in the picture). The tape box has a push button to maintain the same tension. Abduction: running angle by lateral elevation, measured between the midline of the hemibody (goniometer’s arm in line with the ipsilateral posterior superior iliac spine), and the midline of the upper arm (goniometer’s arm in line with the lateral epicondyle of the humerus). Retroflexion: running angle by posterior elevation, measured between the midline of the body (goniometer’s arm in line downward with the trochanter major), and the midline of the upper arm (goniometer’s arm in line with the lateral epicondyle of the humerus). Anteflexion: running angle by anterior elevation, measured between the midline of the body (goniometer’s arm in line downward with the trochanter major), and the midline of the upper arm (goniometer’s arm in line with the lateral epicondyle of the humerus). Endorotation: the thumb as close as possible to C7. The number of vertebrae between C7 and the vertebra that can be reached with the thumb is marked as endorotation measurement. Scapular distance: with the patient’s arms held actively at 90° anteflexion, the distance of the scapula inferior angle to the spine, perpendicularly to the spine, is measured with a tape.

Figure 2

Scapular winging. Scapula alata assessed in TomoBreast patients. (A) Patient 1 pre-RT arms relaxed, (B) Patient 1 pre-RT arms elevated, (C) Patient 2 pre-RT arms relaxed, (D) Patient 2 pre-RT arms elevated, (E) Patient 2 post-RT arms relaxed, (F) Patient 2 post-RT arms elevated, (G) Patient 3 pre-RT arms relaxed and (H) Patient 3 pre-RT arms elevated.

Figure 3

Histograms of shoulder/arm percent changes, according to scapula alata status. Curves, continuous density estimates; SA, scapula alata status pre-radiotherapy, Y-axis, relative frequency density.

Figure 4

Toxicity grades according to scapula alata status. SA, scapula alata pre-radiotherapy status, 0 = absent, 1 = present.