麻豆传媒

For 2024, the American Cancer Society estimated about 299,010 new cases of prostate cancer and about 35,250 prostate cancer deaths. Prostate cancer incidence declined markedly from 2007 to 2014 as changes in screening recommendations led to fewer screenings. Since 2014, however, prostate cancer incidence has risen 3% annually overall, and about 5% annually for advanced-stage disease.¹ The United States (US) Centers for Disease Control and Prevention (CDC) estimates that approximately 13% of men in the US will develop prostate cancer, and that about 2%-3% of men will die of the disease.²

About 15% of those with localized prostate cancer are diagnosed with high-risk disease.³ High-risk prostate cancer is defined as prostate cancer with an American Joint Commission on Cancer (AJCC) tumor stage of at least cT3a, the cancer has an International Society of Urological Pathology Grade Group of 4 or 5 (Gleason score 8-10), or an initial prostate-specific antigen (PSA) level >20.⁴ High-risk cancers are those that have only 1 of these high-risk features, and no features of very high-risk prostate cancer.^4,5 Those with localized high-risk prostate cancer are at an increased risk of recurrence, metastasis, and death.⁴ 

Clinical staging of those with high-risk prostate cancer is essential for deciding on an appropriate treatment strategy. For those with high-risk disease, imaging plays an important diagnostic role, particularly computed tomography (CT) and bone scintigraphy (BS) to detect lymph node and bone metastases.⁶ Those modalities, however, both have serious drawbacks and limitations. In the case of CT scan, early metastases may go undetected due to the high level of cortical destruction needed before bone lesions become visible on CT.⁷ Evidence also attests to poor performance of CT scans for detecting prostate cancer metastases to lymph nodes.⁸ And while BS offers advantages including low cost, wide availability, and performance of whole-body scanning in a single session, it is associated with high false-positive rates.^5,7

The limitations of traditional imaging methods drive clinicians to expand the use of advanced imaging techniques in the staging of high-risk prostate cancer. Once such emerging modality is whole-body magnetic resonance imaging (WBMRI), which can assess both bone and lymph nodes. With the addition of diffusion-weighted imaging (DWI), WBMRI provides an alternative to fluorodeoxyglucose positron emission tomography (PET)-CT with accuracy comparable to PET-CT while avoiding ionizing radiation.⁹

鈥淭here is significant incentive to incorporate advanced imaging modalities to improve the staging of patients with high-risk prostate cancer,鈥� Fang and colleagues wrote, in a recent prospective study conducted to assess the diagnostic accuracy of WBRMI against the combination of CT and BS with or without targeted X-tay (TXR) for the detection of lymph and bone metastases in a large cohort of those newly diagnosed with high-risk prostate cancer. Conducted on patients enrolled between April 2016 and December 2021, study results were published online in September 2024 in Prostate Cancer and Prostatic Diseases.⁵

Within 30 days of evaluation, study participants underwent BS, abdominal and pelvic CT, and WBMRI. The primary endpoint was the performance of each method in detecting metastases to the lymph nodes and bone. The study enrolled 92 participants, among whom lymph metastases were detected in 15 (16.3%) and bone metastases in 8 (8.7%).⁵

The study found that WBMRI outperformed CT in the detecting of lymph metastases, and it performed as well as CT and BS in the detecting bone metastases.⁵

Specifically, for lymph metastases, WBMRI showed: 

• Sensitivity of 0.60 (95% confidence interval [CI], 0.32-0.84)
• Specificity of 0.84 (95% CI, 0.74-0.92) 
• Accuracy of 0.80 (95% CI, 0.71-0.88) 

By comparison, the corresponding values for CT showed:

• Sensitivity of 0.20 (95% CI, 0.04-0.48) 
• Specificity of 0.92 (95% CI, 0.84-0.97) 
• Accuracy of 0.80 (95% CI, 0.71-0.88) 

Regarding bone metastases, WBMRI showed: 

• Sensitivity of 0.25 (95% CI, 0.03-0.65) 
• Specificity of 0.94 (95% CI, 0.87-0.98) 
• Accuracy of 0.88 (95% CI, 0.80-0.94) 

By comparison, the corresponding values for CT with BS were:

• Sensitivity of 0.12 (95% CI, 0-0.53) 
• Specificity of 0.94 (95% CI, 0.870.98) 
• Accuracy of 0.87 (95% CI, 0.78-0.93)

The study found that the sensitivity of WBMRI was significantly greater than that of CT in predicting lymph node metastases (P=.031). However, the study found no significant difference between the specificity (P=.11) and overall accuracy (P>.90) of the 2 imaging modalities. In a receiver operating curve (ROC) analysis, the study found that the area under the curve (AUC) of WBMRI was higher than that of CT, thereby demonstrating an improved discriminatory ability (AUC 0.72 vs 0.56, respectively, P=.019).⁵

For bone metastases, the study found no difference between the sensitivity, specificity, and accuracy of WBMRI versus CT and BS with or without TXR (P>.9). The ROC analysis showed no significant difference in the AUC between WBMRI versus CT and BS (AUC 0.60 vs 0.53, respectively, P=.58).⁵

Limitations included the fact that the study was conducted in a single center, and thus a lower number of distant metastatic cases were identified. Also, besides comparing detection rates, the study did not evaluate how findings from WBMRI influenced clinical decision-making compared with conventional imaging. In addition, the comparisons of imaging modalities did not include PET-CT, another option for primary imaging to stage patients with high-risk prostate cancer.⁵

The study concluded that WBMRI outperforms CT in the detection of lymph metastases and performs as well as CT and BS in the detection of bone metastases among those with high-risk prostate cancer, and the researchers suggested the need for further studies to assess the cost effectiveness of WBMRI and the utility of combined prostate-specific membrane antigen positron emission tomography (PSMA PET) and WBMRI.⁵

鈥淲BMRI positions itself to be incorporated into a one-stop-shop imaging modality that combines MRI and PSMA-PET protocols to improve upon the accuracy of prostate cancer staging,鈥� Fang and colleagues wrote.⁵

Published: December 27, 2024