Comparison of clinical staging algorithms and (111)indium-capromab pendetide immunoscintigraphy in the prediction of lymph node involvement in high risk prostate carcinoma patients

BACKGROUND. The pretherapy prediction of occult lymph node involvement and the avoidance of otherwise futile and potentially morbid definitive local t herapy is paramount in men with newly diagnosed prostate carcinoma. To iden tify patients with prostate carcinoma who likely have lymph node involvemen t and would benefit from staging lymphadenectomy prior to definitive local therapy, the authors compared the ability of several predictive staging alg orithms and a radiolabeled monoclonal antibody scan to predict lymphatic me tastases prior to treatment. METHODS. Between August 1991 and June 1994, 198 men with clinical T2 or T3 classified (TNM) prostate carcinoma (bone scan negative) who were at high r isk of lymph node involvement underwent a In-111-capromab pendetide scan pr ior to staging lymphadenectomy. Several predictive models based on preopera tive pros rate specific antigen level, biopsy Gleason score, and clinical s tage were selected to predict those men having a greater than or equal to 2 0% probability of lymph node involvement. The ability to predict pathologic stage using several clinical algorithms and the monoclonal antibody scan w as compared with pathologic examination of the lymph nodes. RESULTS. Overall, 39% of the pelvic lymph node specimens were positive for metastatic disease by pathologic analysis. Published algorithms predicting lymph node metastases had a positive predictive value (PPV) ranging from 40 .5% to 46.6% and an area under the receiver operating characteristic curve (AUC) ranging from 0.52 to 0.61. The monoclonal antibody scan had a PPV of 66.7% and an AUC of 0.71. The differences between the PPV and the AUC for t he individual clinical algorithms when compared with immunoscintigraphy wer e statistically significant Combining the radiolabeled monoclonal antibody scan with clinical predictive models, a PPV of up to 72.1% could be obtaine d. CONCLUSIONS, These data suggest that the PPVs for the clinical predictive a lgorithms are similar and that the PPV of the radiolabeled monoclonal antib ody scan alone or in combination with the algorithms has additional value i n predicting lymph node involvement in prostate carcinoma patients at high risk of regional disease spread. These algorithms and the In-111-capromab p endetide scan may be used for the appropriate selection of candidates for d efinitive local therapy in men with clinically localized prostate carcinoma and significant risk of lymph node involvement. (C) 1999 American Cancer S ociety.