Mixed low and high grade non muscle invasive bladder cancer: a histological subtype with favorable outcome

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1 DOI /s Original Article Mixed low and high grade non muscle invasive bladder cancer: a histological subtype with favorable outcome Tina Schubert Matthew R. Danzig Srinath Kotamarti Rashed A. Ghandour Danny Lascano Byron P. Dubow G. Joel Decastro Mitchell C. Benson James M. McKiernan Received: 28 June 2014 / Accepted: 11 August 2014 Springer-Verlag Berlin Heidelberg 2014 Abstract Objective To determine whether heterogeneity of tumor grade affects the response to Bacillus Calmette-Guérin (BCG) treatment for patients with non-muscle-invasive bladder cancer (NMIBC). Methods Patients with Ta or T1 NMBIC receiving a 6-week induction course of intravesical BCG therapy after transurethral resection were divided according to the tumor grade. Clinical and pathological variables were compared. Advanced intervention-free survival (AIFS), defined as duration of freedom from advanced intervention (including non-bcg intravesical agents or cystectomy) or metastasis, was plotted using Kaplan Meier methods. The effect of grade on survival duration was assessed by multivariate Cox proportional hazards modeling. Results One hundred and fifty-three patients were identified: 17 with mixed low- and high-grade (MG) and 136 with pure high-grade (PHG) NMIBC. Demographic and additional pathologic variables were comparable between groups (p > 0.05). Five-year AIFS was 88.2 % for MG patients, compared to 48.5 % for PHG patients (p = by log-rank test). On multivariate analysis, PHG was an independent risk factor for worse AIFS (HR 4.4, 95 % CI , p = 0.040). Among patients failing to respond to primary BCG induction, who underwent a secondary induction of BCG with interferon, MG patients had better response than PHG patients (100 vs %, p = 0.035). T. Schubert M. R. Danzig (*) S. Kotamarti R. A. Ghandour D. Lascano B. P. Dubow G. J. Decastro M. C. Benson J. M. McKiernan Department of Urology, Herbert Irving Cancer Center, Columbia University College of Physicians and Surgeons, 161 Fort Washington Avenue, Herbert Irving Pavilion 11th Floor, New York, NY 10032, USA danzig.matthew@gmail.com Conclusions Mixed low- and high-grade NMIBC exhibits a significantly better response profile to intravesical BCG therapy compared to PHG NMIBC. The implications of these results are that less aggressive treatment strategies for this unique cancer entity may be needed and that there is a benefit to the reporting of tumor heterogeneity in transurethral resection of bladder tumor specimens. Keywords Bladder cancer BCG vaccine Mixed grade Prognosis Introduction Urothelial carcinoma of the bladder (UCB) is the most costly malignancy to treat, with one of the highest recurrence rates of all solid tumors [1 4]. Approximately 70 % of UCB patients initially present with non-muscle-invasive bladder cancer (NMIBC) [1]. Tumor grade is a well-established determinant of therapeutic options and prognosis. Grading of UCB has historically been controversial. In 1998, the World Health Organization (WHO) G1-G3 classification system was replaced by a binary low- or high-grade system [5]. Tumors are classified based on the highest grade in the pathological specimen, and heterogeneity is therefore not reflected. There is no consensus regarding the minimal percentage required to classify a tumor as high grade (HG), so tumors are often labeled as such even with only a small HG focus. Studies have demonstrated a high prevalence (28 32 %) of UCB specimens containing different histological grades within the same tumor [6, 7]. Pathologists often describe such tumors as focally low and high grade (mixed grade, MG). The optimal clinical course for patients presenting with a heterogeneous grade has not yet been elucidated; such patients have most likely been treated as having pure HG NMIBC.

2 Bacillus Calmette-Guérin (BCG) treatment after transurethral resection of bladder tumor (TURBT) is the standard of care for HG UCB patients [1, 8]. This approach offers superior prevention of recurrence and progression in high-risk patients compared to TURBT alone [9 13]. However, BCG can have toxicities including urinary frequency and chemical cystitis as well as more severe side effects like fever, prostatitis, liver toxicity, and BCG sepsis [14, 15]. Despite evidence that consideration of tumor heterogeneity improves prognostic accuracy for UCB [6], the response of heterogeneous NMIBC tumors to BCG therapy is understudied. We sought to compare the BCG response of patients with MG NMIBC to those with pure HG disease. Materials and methods The IRB-approved Columbia Urologic Oncology Database was queried for patients with Ta or T1 NMIBC receiving a 6-week induction course of intravesical BCG from 2008 to Electronic medical records were reviewed. One hundred and fifty-three patients were identified who were initially diagnosed with MG or pure HG NMIBC. None of the included patients received radiotherapy prior to, or interferon (INF) along with, initial BCG induction. Exclusion criteria were initial pure carcinoma in situ (Tis) (41), systemic chemotherapy prior to induction (3), or follow-up less than 6 months (2). All specimens were obtained during TURBT and staged according to the 1997 TNM staging system: Ta noninvasive papillary UCB; T1 UCB invading lamina propria; Tis carcinoma in situ. Tumor grade was determined by review of original pathology reports, in accordance with the 2004 WHO and International Society of Urological Pathology (ISUP) system which divides neoplasms into the categories of: urothelial neoplasm of low malignant potential (none identified in our study); low-grade UCB; and HG UCB. Tumors described as having low-grade and HG features within the same lesion, but <50 % HG components, were considered MG (reports such as predominantly lowgrade with several HG foci ). Tumors described as having more than 50 % HG components, or HG components only, were considered HG (for example, mainly high grade and focally low grade ). In cases of multifocal disease, each lesion was considered separately. A 50 % cutoff was used because prior evidence suggests a difference in prognosis between HG-containing tumors whose primary grade is high and those whose primary grade is low [6]. All patients were treated with an initial TURBT and underwent 6 weekly intravesical instillations of 81 mg BCG followed by surveillance cystoscopy and cytology. For the first 2 years, patients were followed quarterly, then semiannually for 3 years, and annually thereafter. Response status was evaluated through histopathological results of follow-up cytologies and cystoscopies. Positive findings were treated according to current guideline recommendations. Outcome was defined as BCG response if remission was achieved after one or two BCG induction courses, with or without maintenance therapy. BCG non-response was defined as persistent or recurrent disease necessitating another treatment strategy, including addition of INF, intravesical chemotherapy, repetitive TURBTs, radical cystectomy (RC), or progression to metastatic disease. We chose this composite outcome rather than analyzing recurrence rates and recurrence-free survival because we sought to compare the rates at which patients could be successfully treated using BCG alone without requiring additional, intensive interventions. In this way, we avoided conflating minor recurrences treatable by a second BCG induction course with the development of more aggressive or metastatic disease. Associations between tumor grade and categorical variables were assessed using the chi-square test. Differences between continuous variables were compared using Student s t test. Duration of time from primary BCG induction to BCG non-response (receipt of additional treatment modality or discovery of metastatic progression) was plotted using Kaplan Meier methods, stratified by initial tumor grade. This duration was termed advanced intervention-free survival (AIFS). Differences in AIFS were assessed by logrank test. A multivariate Cox proportional hazards model was created to determine the effect of initial grade on AIFS duration when controlling for clinical and pathological cofactors. To test for over-fitting, a second model was constructed with fewer variables. All p values are the result of 2-sided tests, and significance was defined as p Analyses were performed using SPSS 21.0 (IBM Corp, Armonk, NY). Results One hundred and fifty-three patients meeting inclusion criteria were followed for a median of 27.6 months (range 6 84). Seventeen patients (11 %) had HG and 136 patients (89 %) had pure HG NMIBC. Demographic and pathologic features of the cohort are detailed in Table 1. Seventy-five percent were male, with a median age at primary induction of 71.0 years (range 32 93). Fifty-six percent had stage T1 disease initially and 44 % had stage Ta. Thirty-six percent had multifocal disease, 22 % had concomitant CIS, and 6 % had a history of pure low-grade disease prior to the present diagnosis. Fifteen out of 17 patients (88.2 %) with MG disease responded to BCG therapy, while 2 (11.8 %) required an additional treatment strategy. In contrast, only

3 Table 1 Clinicopathologic characteristics and clinical interventions of the 153 patients receiving intravesical Bacillus Calmette-Guérin treatment for non-muscle-invasive urothelial carcinoma of the bladder Categorical variables No. (%) Initial pathology stage Ta 67 (43.8) T1 86 (56.2) Initial pathology grade Low + high 17 (11.1) High 136 (88.9) Focality Single 98 (64.1) Multifocal 55 (35.9) Concomitant CIS No 119 (77.8) Yes 34 (22.2) History of low-grade disease No 144 (94.1) Yes 9 (5.9) Race White 126 (82.4) Black 7 (4.6) Hispanic 10 (6.5) Other 10 (6.5) Gender Male 115 (75.2) Female 38 (24.8) Smoking history No 44 (28.8) Yes 109 (71.2) Most aggressive intervention received BCG only 89 (58.2) Repetitive TURBT 11 (7.2) Additional intravesical agents 27 (17.6) Radical cystectomy 26 (17.0) Continuous variables Mean (SD) Initial tumor size (cm) 2.2 (1.8) Age at primary BCG induction (years) 69.6 (11.8) Follow-up time (months) 31.6 (19.1) Patients whose most aggressive intervention was repetitive TURBT were BCG non-responders who did not undergo more aggressive interventions due to advanced comorbidities and/or refusal of cystectomy 74 of 136 patients (54.4 %) in the HG group responded, while 62 (45.6 %) underwent further clinical interventions beyond BCG (45.6 vs %, p = 0.008). Aside from grade, there were no statistical differences in clinicopathologic characteristics between BCG responders and non-responders. Fig. 1 Kaplan Meier survival analysis, stratified by initial tumor grade, for advanced intervention-free survival. This was defined as the duration of time from primary BCG induction to BCG nonresponse (receipt of additional treatment modality such as alternate intravesical agents or cystectomy, or discovery of metastatic progression) Figure 1 depicts a Kaplan Meier survival analysis for AIFS, stratified by initial grade. There was a significant difference in the AIFS distributions of HG versus MG patients as assessed by log-rank test (p = 0.030). Two-year AIFS and five-year AIFS for the HG cohort were 53.9 % and 48.5 %, respectively. Two-year AIFS and five-year AIFS for the MG cohort were both 88.2 %. Multivariate Cox regression analysis, shown in Table 2, confirmed that patients with MG tumors were more likely to respond to BCG treatment when adjusting for other key features (HG hazard ratio = 4.4, 95 % CI , p = 0.040). In the revised model created to avoid error by over-fitting, only six variables were included in proportion with the 64 events. Initial grade remained a significant predictor of response (Table 2). All comparisons of demographic and pathologic characteristics between patients with MG and HG tumors were non-significant (p 0.05); however, there were trends toward a higher proportion of initial T1 pathology (54 vs. 47 %), a higher proportion of African Americans (6.8 vs. 0 %), and a higher proportion of patients with recorded smoking histories (69 vs. 60 %) in the HG cohort.

4 Table 2 Univariate and multivariate Cox proportional hazards modeling, demonstrating the impact of clinical and pathological variables on response to intravesical Bacillus Calmette-Guérin treatment and freedom from advanced interventions or metastatic progression Univariate Cox regression Multivariate Cox regression Revised multivariate HR 95 % CI p value HR 95 % CI p value HR 95 % CI p value Initial pure high-grade disease (vs. mixed grade) Initial T1 pathology (vs. Ta) Multifocality Concomitant Tis History of low-grade disease Race White Referent Referent Black Hispanic Others Female gender Smoking history Age at primary BCG induction Initial tumor size (mm) Significant p-values are bolded A second, simplified multivariate model was constructed in order to test for over-fitting, on the principle of including no more than one variable in a model for every ten events HR Hazard ratio Four of 15 MG responders (27 %) and 7 of 74 HG responders (10 %) did not receive maintenance instillations due to persistent side effects during induction; this difference was not statistically significant (p = 0.07). Follow-up duration for responders was similar to the cohort overall (median 28.3 months, range 7 69). Two MG patients required additional treatment; one had recurrent stage Ta disease following induction, and the other progressed from Ta to T1 NMIBC. In comparison, 48 of 62 HG patients (77 %) requiring additional treatment developed same- or lower-stage recurrence [5 (8 %) with lower T-stage; 27 (43 %) with the same T-stage; 16 (26 %) with Tis only]; and 14 (23 %) had disease progression. The stage distribution on recurrence or progression among HG patients requiring additional treatment was 16 (26 %) Tis, 13 (21 %) Ta, 27 (43 %) T1, and 6 (10 %) T2. This distribution did not differ significantly from that of the two MG patients (p = 0.69). Both MG patients received a second BCG induction cycle with INF and both responded. This was a significantly higher response rate than the 19 HG patients undergoing a second BCG induction course with INF, of whom 5 responded (100 vs. 26 %, p = 0.035). HG patients who failed primary BCG induction and who failed or never received a secondary BCG + INF induction course were treated with additional intravesical agents, repetitive TURBTs, RC, or some combination thereof. Discussion Tumor grade has long been recognized as an important predictor of disease recurrence and progression [16 19]. The new grading classification of the WHO and ISUP attempts to avoid the classification of intermediate grade tumors and was partly motivated by concerns of overtreatment of patients with heterogeneous histological characteristics [5]. The prognostic significance of tumor heterogeneity under the new high-low grading classification was first studied by Cheng et al. in 1999 shortly after the revision was proposed. The authors assessed the relationship between grade and progression-free survival among 164 UCB patients undergoing TURBT and various additional treatments. They found a high rate of grade heterogeneity (32 %) and concluded that consideration of tumor heterogeneity increases prognostic accuracy and that heterogeneous tumors may have a more favorable treatment response profile compared to HG tumors [6]. However, their study included many treatment modalities, and only 7 patients (4.3 %) received BCG, precluding a comparison of BCG

5 response rates with the present study. Subsequently, Bills et al. analyzed 293 UCB patients and also noted extensive heterogeneity (28 %) [7]. The authors did not analyze clinical outcomes, but theorized that consideration of heterogeneity would be important in future prognostic studies. In our study, patients with Ta or T1 NMIBC tumors of MG had a significantly better response to intravesical BCG treatment compared to HG patients, and therefore a reduced need for more aggressive treatments such as intravesical chemotherapy or RC. This supports the reporting of tumor heterogeneity and may imply the need for less aggressive treatment strategies for select heterogeneous tumors. In contrast, Krueger et al. did not identify grade heterogeneity as a predictor of prognosis for patients with muscle invasive UCB. However, with a marginally significant p value of 0.07, the authors concluded that a consideration of heterogeneity may improve the predictive power of the WHO/ISUP system [20]. NMIBC was not included. The clinical behavior of NMIBCs with MG histology is understudied. To our knowledge, only Gofrit et al. [21] have analyzed BCG response rates and clinical outcomes in MG NMIBC compared to homogenous disease. The authors concluded that progression-free survival was comparable in low-grade and MG NMIBC and worse in HG. This group defined tumors containing >10 % HG characteristics as pure HG and <10 % HG characteristics as MG. The precise degree of HG histology within a heterogeneous tumor needed to predict more aggressive clinical behavior is unclear and requires larger studies to resolve. Gofrit et al. s results and those of the present study suggest that investigations of modified intravesical strategies may be warranted for patients with MG tumors. Induction BCG instillations are classically given according to the 6-weekly schedule introduced by Morales et al. [22]. For optimal efficacy, maintenance treatments are currently recommended [1]. However, the optimal frequency, duration, and dosage of maintenance instillations remain unclear. Recent evidence suggested that an extended maintenance schedule with 3 years of full dose BCG reduces the risk of recurrence in high-risk but not intermediate-risk patients [23]. The benefit of this regimen for patients with heterogeneous NMIBC has not been evaluated. In our study nearly one-third of the MG patients did not receive maintenance instillations due to persistent side effects during induction. None of these patients experienced recurrence, with a follow-up duration of at least 1 year. Our results reflect the possibility that patients with MG tumors may not require a maintenance schedule as aggressive as HG patients, though confirmation by larger studies is needed. Limitations of our study include its retrospective design, variable duration of follow-up, and our lack of a comparison group of patients with pure low-grade disease undergoing intravesical BCG therapy. We were also unable to include a comparison group of contemporary patients with comparable risk profiles who were candidates for BCG but did not receive it. Thus, we cannot determine the extent to which our results reflect an interaction between grade and BCG treatment, versus an effect of superior baseline prognosis of MG patients. However, since first-line treatment with BCG is the present standard of care, we feel that this does not diminish the clinical utility of our results. In addition, standardized pathological re-review of specimens was not carried out, and it is possible that in our HG cohort, we inadvertently included some MG patients in cases where the pathologist failed to report heterogeneity. However, this would tend to make the two groups more similar, biasing our study in the direction of failing to detect a difference. We observed a significant difference in outcome between the groups despite this potential cross-contamination. Confirmation of our results in multiinstitutional studies with larger cohorts is necessary before drawing actionable conclusions. A standardized pathological definition of MG UCB would facilitate investigation of this novel and understudied disease entity. In summary, patients with MG NMIBC have a better outcome following BCG therapy compared to patients with HG tumors. This suggests that histological classification of NMIBC in a binary system may mask important prognostic information and that reporting of MG tumors may be beneficial. Validation of these findings could allow for a safe reduction in the use of toxic BCG regimens for MG patients. Furthermore, it may be useful to consider grade heterogeneity in the development of new risk stratification systems for NMIBC. Conflict of interest The authors declare that they have no conflict of interest. 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