Neoadjuvant chemotherapy–related histologic changes in radical cystectomy: assessment accuracy and prediction of response

SummaryWe evaluated the spectrum of histologic changes associated with neoadjuvant chemotherapy (NAC) and compared them with those resulting from transurethral resection (TUR). Twenty-five patients who received NAC were divided based on both their preoperative clinical/radiographic findings (clinical stage, hydronephrosis, palpable mass) and the cystectomy (RC) findings into NAC respondents (advanced clinical stage and < pT2 + pN0), possible NAC respondents (non–advanced clinical stage and < pT2 + pN0), and NAC nonrespondents (≥ pT2and/or ≥ pN1). In addition, 14 patients who received TUR alone and had < pT2 + pN0 on RC were included. Presence/absence of the following histologic features was assessed: fibrosis/myofibroblastic reaction, hyalinization in the bladder wall, inflammatory reaction, calcification, foreign-body giant cells, necrosis, sheets of foamy macrophages, and fibrosis/hyalinization/necrosis in the lymph nodes (LNs). Overall, there was a significant histologic overlap between all groups. However, patients who received NAC had a significantly higher likelihood of showing hyalinization and less giant cells and inflammatory reaction than did those who received TUR only. Moreover, the only significantly different histologic features in NAC respondents versus TUR respondents were hyalinization and LN changes, with those 2 features in 25% and 0% of the possible NAC respondents group, respectively. Lastly, there was no significant difference in the possible NAC respondent group in comparison to the TUR-only arm. It appears that TUR and NAC result in overlapping histologic changes. In cases with no/minimal residual disease on RC, it is difficult to attribute the changes to NAC effect only, except if (1) hyalinization of the bladder wall or LN changes are present, or (2) if the preoperative clinical stage was beyond what could be resected by TUR.