Predictive factors for adrenal metastasis in extra-adrenal cancer patients with an adrenal mass
The adrenal gland is a frequent site of metastasis in patients with extra-adrenal malignancies. Adrenal masses are often incidentally observed during staging work-up or imaging follow-up in patients with extra-adrenal cancer. Therefore, it is necessary to distinguish between benign adrenal lesions and metastases in extra-adrenal cancer patients with adrenal masses to develop an appropriate management plan. We retrospectively evaluated the predictive factors for adrenal metastasis in extra-adrenal cancer patients with adrenal masses.
We retrospectively reviewed the medical records of extra-adrenal cancer patients with adrenal mass on cancer staging work-up or follow-up study who subsequently underwent adrenalectomy in our institution between September 2003 and June 16. All patients underwent functional studies, and those with a positive result on a functional study were excluded. The characteristics of oncology patients with adrenal masses such as age, sex, body mass index, smoking, mass location, mass size, hypertension, diabetes mellitus, pre-contrast Hounsfield unit (HU), and synchronous or metachronous adrenal mass at the time of extra-adrenal cancer diagnosis were analyzed.
Of the total 68 extra-adrenal cancer patients with adrenal masses, 23 were confirmed to have adrenal metastasis pathologically. The primary cancers included hepatocellular cell carcinoma (n = 7), renal cell carcinoma (n = 7), lung cancer (n = 4), colon cancer (n = 3), and breast cancer (n = 1). On multivariate analysis, a higher pre-contrast HU (p = 0.001; odds ratio [OR], 1.105; 95% confidence interval [CI], 1.042–1.172), male sex (p = 0.019; OR, 9.782; 95% CI, 1.462–65.461), and synchronous adrenal mass at the time of the cancer diagnosis (p = 0.007; OR, 11.090; 95% CI, 1.937–63.490) were observed as predictive factors for adrenal metastasis in extra-adrenal cancer patients with adrenal masses. The cut-off value of pre-contrast HU to distinguish between a metastasis and a benign tumor was 36.24 (sensitivity, 81.8%; specificity, 91.3%).
A high pre-contrast HU (>36), male sex, and synchronous adrenal mass at the time of the cancer diagnosis are predictive factors for adrenal metastasis in extra-adrenal cancer patients with adrenal masses.