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Thymic hyperplasia after high-dose chemotherapy and autologous stem cell transplantation: incidence and significance in patients with breast cancer.

OBJECTIVE
The purpose of this study was to determine the incidence and clinical significance of thymic hyperplasia after high-dose chemotherapy and autologous stem cell transplantation for treatment of metastatic or high-risk primary (with at least four positive lymph nodes) breast cancer.


MATERIALS AND METHODS
We retrospectively reviewed clinical records and CT scans of 102 breast cancer patients treated with high-dose chemotherapy and autologous stem cell transplantation. Patients were 26-63 years old (mean, 46 years). The length and width of the thymus gland were measured on serial CT scans obtained before and after treatment. Moderate thymic hyperplasia was recorded if a focal or diffuse increase was seen in the oblong, triangular soft-tissue opacity conforming to the configuration of the normal gland within the anterior mediastinum after therapy. Minimal hyperplasia was recorded when a minimal increase was seen in soft-tissue attenuation conforming to the configuration of the normal bilobed thymus gland within the anterior mediastinum, but no discrete mass was visible.


RESULTS
CT showed no thymic hyperplasia in 91 (89%) of the 102 patients. CT showed thymic hyperplasia in the other 11 patients (11%). Three patients (3%) had moderate hyperplasia, and eight patients (8%) had minimal hyperplasia. When comparing patients with and without hyperplasia, we found no difference in mean age or survival.


CONCLUSION
Thymic hyperplasia is rare after high-dose chemotherapy and autologous stem cell transplantation in adult patients with metastatic or high-risk primary breast cancer. In this population, thymic hyperplasia does not appear to correlate with survival.