Utility of Bone Scan in Evaluating Patients with Clinically Indeterminate Diagnosis of Cancer in a Low-resource Practice.

Context: A major indication for referrals for bone scans (BS) to establish or exclude skeletal metastases. Few patients are referred with clinically indeterminate diagnosis or cancer of unknown primary (CUP), to search for bony metastases or primary tumor.

Aims: This study aimed to assess the usefulness or otherwise for BS in such instances.

Settings and design: A retrospective cross-sectional study of BS performed for CUP and indeterminate diagnosis from 2012 to 2016 in the nuclear medicine unit of a tertiary teaching hospital.

Subjects and methods: The study involved reviews of technetium-99m diphosphonate BS for patients with CUP. BSs were reported by nuclear physicians as normal, normal variants, suspicious for metastases or as malignant, and with solitary or multiple skeletal metastases.

Statistical analysis used: Data were analyzed using SPSS version 21 for descriptive analysis. Continuous data were displayed as means along with their standard deviation; categorical data were tabulated as frequencies and percentages.

Results: Of 2156 BS, 42 (0.02%) were eligible. Patients were aged 27-86 years, mainly in the sixth and seventh decades of life. Bone metastases were identified in 14 (33%) of these patients, whereas 17 BS (40%) were normal, BS appeared equivocal in 10 (23.8%).

Conclusions: Single-photon emission computed tomography/computed tomography availability would resolve the clinical dilemma in patients with equivocal and apparently normal BS.