Prostate-specific antigen for prediction of skeletal metastases on bone scintigraphy in prostate cancer

Dear Editor,

We read with great interest the article by Manohar et al.[1] in the July–September 2020 edition of the journal. They conducted a retrospective analysis of medical records on 307 prostate cancer patients referred for 99mTc methylene diphosphonate (99mTc MDP) bone scintigraphy in a nuclear medicine department in India and used receiver operator curve analysis to determine the optimal prostate-specific antigen (PSA) cutoff values for predicting skeletal metastases. The authors reported that the optimal cutoff value of serum PSA in the prediction of positive bone scan for skeletal metastases was 29.16 ng/ml, with a sensitivity and specificity of 89.0% and 74.6%, respectively. They reviewed similar studies on the subject from different settings which showed that the PSA cutoff for bone scintigraphy ranged from 10 to >30 ng/ml.[1]

In resource-limited settings where the practice of nuclear medicine remains challenging due to numerous factors including limited facilities and erratic radiopharmaceutical supply,[2] there continues to be a need to identify the predictive factors that will aid the optimal use of nuclear medicine facilities and resources as this will facilitate patient management and improve clinician satisfaction with the services provided by the nuclear medicine. Our group in 2019 published the results of a retrospective study on PSA and the risk of bone metastases in West Africans with prostate cancer in which 96 (26.5%) out of 363 study patients had skeletal metastases on 99mTc MDP bone scan.[3] In our study, a PSA cutoff value of ≥20 predicted the presence of skeletal metastases with a sensitivity and specificity of 86.5% and 41.2%, respectively. Although a cutoff value of ≥30 predicted the presence of metastases with a lower sensitivity of 72.9%, the specificity was higher at 56.2%, and 60% of cases were correctly classified. Similar to the current study by Manohar et al.[1] which reported an accuracy of 87%, we found that PSA had an accuracy of 72% in the prediction of skeletal metastases on bone scan.

Ritenour et al.[4] in their study fixed the cutoff point for serum PSA for which bone scans must be acquired at >30 ng/ml, a finding which further supports the 29.16 ng/ml cutoff proposed by Manohar et al.[1] The serum PSA cutoff values in the West African population we studied were not so different from that of the Indian population.[1],[5] We like Ritenour et al.[4] showed that Gleason score ≥8 had an increased specificity for the detection of bone metastases in prostate cancer. We were able to show in our study that both serum PSA and Gleason score were able to predict the presence of metastases with reasonable accuracy at 72% and 68%, respectively.[3]

We agree with Manohar et al.[1] that serum PSA is an independent predictor of bone metastases in patients with prostate cancer. Bone scintigraphy may not be useful as a routine staging investigation, especially in asymptomatic low-to-intermediate risk patients with prostate cancer in resource-limited settings.

Conflict of Interest

There are no conflicts of interest.

Financial support and sponsorship

Nil.

• References

• 1 Manohar P, Rather T, Khan S. Determination of the optimal cut-off value of serum prostate-specific antigen in the prediction of skeletal metastases on technetium-99m whole-body bone scan by receiver operating characteristic curve analysis. World J Nucl Med 2020;19:255-9.
• 2 Adedapo KS, Onimode YA, Ejeh JE, Adepoju AO. Avoidable challenges of a nuclear medicine facility in a developing nation. Indian J Nucl Med 2013;28:195-9.
• 3 Amoako YA, Hammond ENB, Assasie-Gyimah A, Laryea DO, Ankrah A, Amoah G. Prostate-specific antigen and risk of bone metastases in west Africans with prostate cancer. World J Nucl Med 2019;18:143-8.
• 4 Ritenour CW, Abbott JT, Goodman M, Alazraki N, Marshall FF, Issa MM. The utilization of Gleason grade as the primary criterion for ordering nuclear bone scan in newly diagnosed prostate cancer patients. Sci World J 2009;9:1040-5.
• 5 Kamaleshwaran KK, Mittal BR, Harisankar CN, Bhattacharya A, Singh SK, Mandal AK. Predictive value of serum prostate specific antigen in detecting bone metastasis in prostate cancer patients using bone scintigraphy. Indian J Nucl Med 2012;27:81-4.

Publikationsverlauf

Eingereicht: 24. September 2020

Angenommen: 28. Oktober 2020

Artikel online veröffentlicht:
24. März 2022