Does intensity-modulated radiation therapy by helical tomotherapy for prostate cancer increase the subsequent risk of bladder cancer? A propensity score-matched analysis

OBJECTIVES

This study aimed to evaluate the risk of bladder cancer after intensity-modulated radiation therapy (IMRT) using helical tomotherapy for prostate cancer in comparison to the risk post-radical prostatectomy (RP) using propensity score-matched analysis and to assess the risk factors for bladder cancer.

METHODS

This retrospective study included 2067 patients with non-metastatic prostate cancer treated at our institution between June 2007 and December 2016. Of these, 1547 patients were treated with IMRT and 520 underwent RP. The propensity scores were calculated using age, National Comprehensive Cancer Network risk classification, prostate volume, Brinkman index, and follow-up time as matched covariates. A propensity score-matched patient cohort (n = 718; IMRT: 359, RP: 359) was created, and the risk of bladder cancer after treatment was compared.

RESULTS

In total, bladder cancer was detected in 33 patients. Five patients in the IMRT group and one in the RP group died of bladder cancer. In the propensity score-matched analysis, the 5-year bladder cancer-free survival rate was significantly lower in the IMRT group than in the RP group (91.7% and 96.2%, respectively; p < 0.001). Multivariate analysis revealed that IMRT and the Brinkman index were the risk factors for bladder cancer in this cohort (odds ratio = 5.085, 95% confidence interval = 1.436-18.008, p = 0.012 and odds ratio = 1.001, 95% confidence interval = 1.000-1.001, p = 0.010, respectively).

CONCLUSIONS

IMRT for prostate cancer using helical tomotherapy increases the subsequent risk of bladder cancer compared with RP and is an independent risk factor for bladder cancer similar to smoking.

Impact of Advanced Radiotherapy on Second Primary Cancer Risk in Prostate Cancer Survivors: A Nationwide Cohort Study

Purpose

External Beam Radiotherapy (EBRT) techniques dramatically changed over the years. This may have affected the risk of radiation-induced second primary cancers (SPC), due to increased irradiated low dose volumes and scatter radiation. We investigated whether patterns of SPC after EBRT have changed over the years in prostate cancer (PCa) survivors.

Materials and Methods

PCa survivors diagnosed between 1990-2014 were selected from the Netherlands Cancer Registry. Patients treated with EBRT were divided in three time periods, representing 2-dimensional Radiotherapy (RT), 3-dimensional conformal RT (3D-CRT), and the advanced RT (AdvRT) era. Standardized incidence ratios (SIR) and absolute excess risks (AER) were calculated to estimate relative and excess absolute SPC risks. Sub-hazard ratios (sHRs) were calculated to compare SPC rates between the EBRT and prostatectomy cohort. SPCs were categorized by subsite and anatomic region.

Results

PCa survivors who received EBRT had an increased risk of developing a solid SPC (SIR=1.08; 1.05-1.11), especially in patients aged <70 years (SIR=1.13; 1.09-1.16). Pelvic SPC risks were increased (SIR=1.28; 1.23-1.34), with no obvious differences between the three EBRT eras. Non-pelvic SPC were only significantly increased in the AdvRT era (SIR=1.08; 1.02-1.14), in particular for the 1-5 year follow-up period. Comparing the EBRT cohort to the prostatectomy cohort, again an increased pelvic SPC risk was found for all EBRT periods (sHRs= 1.61, 1.47-1.76). Increased non-pelvic SPC risks were present for all RT eras and highest for the AdvRT period (sHRs=1.17, 1.06-1.29).

Conclusion

SPC risk in patients with EBRT is increased and remained throughout the different EBRT eras. The risk of developing a SPC outside the pelvic area changed unfavorably in the AdvRT era. Prolonged follow-up is needed to confirm this observation. Whether this is associated with increased irradiated low-dose volumes and scatter, or other changes in clinical EBRT practice, is the subject of further research.

The Impact of Radiotherapy on the Incidence of Secondary Malignancies: A Pan-Cancer Study in the US SEER Cancer Registries

The population of cancer patients with second primary malignancies (SPMs) is rapidly growing. The relationship between radiotherapy and SPMs for some types of tumors is unknown or debated. In this study, we identify 24 types of first primary malignancies (FPMs) between 2004 and 2015 in the Surveillance, Epidemiology, and End Results (SEER) database. Patients in the radiotherapy group were matched to those in the no radiotherapy group with a matching ratio of 1:1. After propensity-score matching (PSM), additional competing risk regression analyses were performed to calculate the efficacy of radiotherapy to SPMs in the PSM-adjusted population. In addition, the Fine and Gray model was utilized in the primary cohorts, and stratified analyses were performed based on surgery. This study includes a total of 2,831,789 eligible patients with tumors diagnosed from 2004 to 2015 in the SEER 18 database, amongst whom 100,194 (3.5%) patients developed SPMs. We observe higher risks of SPMs associated with radiotherapy in several types of tumors in the PSM-adjusted populations (small bowel adenocarcinoma, small cell lung carcinoma, prostate adenocarcinoma, urinary bladder transitional cell carcinoma, invasive ductal breast carcinoma, invasive lobular breast carcinoma, and Hodgkin lymphoma). The results in the PSM-adjusted populations were consistent with outcomes in the multivariable competing risk models. Meanwhile, in subgroup analyses stratified by surgery, some other types of tumor (except for those with positive results in the PSM-adjusted cohorts) with radiotherapy were also associated with a higher prevalence of SPMs in the subgroups of surgical treatment (pancreatic adenocarcinoma, rectal adenocarcinoma, lung adenocarcinoma and follicular thyroid carcinoma in the surgery subgroups). The impact of radiotherapy on the incidence of secondary malignancies is distinct in different types of cancer. These findings merit further investigation and may ultimately impact treatment decision-making for tumor management.

Spectrum and Incidence Trends of AIDS- and Non-AIDS-Defining Cancers between 2010 and 2015 in the French Dat'AIDS Cohort

BACKGROUND

Cancer risk is higher in people living with HIV (PLWH) compared with the general population, and cancers related to age are expected to be most prevalent.

METHODS

We determined the spectrum and incidence rates of AIDS-defining cancers (ADC) and non-AIDS-defining cancers (NADC) and of lung, Hodgkin lymphoma (HL), head and neck (HNC), colon-rectum, anal, liver, breast, prostate, and urinary bladder cancers between January 2010 and December 2015 in the French Dat'AIDS cohort. Incidence rates were calculated by year and compared using the χ ² test for linear trend. Standardized incidence ratios [SIR (95% confidence interval)] were calculated relative to the French general population.

RESULTS

Among 44,642 patients, corresponding to 180,216.4 person-years (PY), 1,440 cancer cases occurred in 1,314 patients. ADC incidence was 191.4 (172.3-212.7)/10⁵ PY and declined over time overall and in men, whereas NADC incidence was higher [548.8 (515.6-584.1)/10⁵ PY] and did not change. In men, non-Hodgkin lymphoma was the most common cancer, but prostate cancer had the highest incidence among NADCs. Breast cancer was the most common cancer in women. SIRs were higher for cervical cancer [1.93 (1.18-3.14)], HNC in women [2.4 (1.4-4.2)], liver [overall: 3.8 (3.1-4.6); men: 3.2 (2.5-4.0); women: 12.9 (8.3-20.0)], and HL [overall: 13.8 (11.1-17.1); men: 16.2 (12.9-20.4); women: 6.2 (3.22-11.9)] but lower for lung [overall: 0.7 (0.6-0.9); men: 0.7 (0.5-0.8)], prostate [0.6 (0.5-0.7)], and breast cancers [0.6 (0.4-0.7)].

CONCLUSIONS

Spectrum of NADCs has changed, with prostate and breast cancers becoming the most common despite their lower SIR.

IMPACT

These results confirm the need to maintain regular epidemiologic cancer monitoring in order to update screening guidelines.

The Risk of Second Primary Cancers in Prostate Cancer Survivors Treated in the Modern Radiotherapy Era

Purpose

Concerns have been raised that modern intensity modulated radiotherapy (IMRT) may be associated with increased second primary cancer risks (SPC) compared to previous three-dimensional conformal radiation techniques (3DCRT), due to increased low dose volumes and more out-of-field ionizing dose to peripheral tissue further away from the target. We assessed the impact of treatment technique on SPC risks in a cohort of prostate cancer (PCa) survivors.

Material and Methods

The study cohort comprised 1,561 PCa survivors aged 50–79 years at time of radiotherapy, treated between 2006–2013 (N=707 IMRT, N=854 3DCRT). Treatment details were extracted from radiotherapy systems and merged with longitudinal data of the Netherlands Cancer Registry to identify SPCs. Primary endpoint was the development of a solid SPC (excluding skin cancer) in peripheral anatomical regions, i.e. non-pelvic. Applied latency period was 12 months. SPC rates in the IMRT cohort (total cohort and age subgroups) were compared to 1) the 3DCRT cohort by calculating Sub-Hazard Ratios (sHR) using a competing risk model, and 2) to the general male population by calculating Standardized Incidence Ratios (SIR). Models were adjusted for calendar period and age.

Results

Median follow-up was 8.0 years (accumulated 11,664 person-years at-risk) with 159 cases developing ≥1 non-pelvic SPC. For IMRT vs 3DCRT we observed a significantly (p=0.03) increased risk (sHR=1.56, 95% Confidence Interval (CI) 1.03–2.36, corresponding estimated excess absolute risk (EAR) of +7 cases per 10,000 person-years). At explorative analysis, IMRT was in particular associated with increased risks within the subgroup of active smokers (sHR 2.94, p=0.01). Within the age subgroups 50–69 and 70–79 years, the sHR for non-pelvic SPC was 3.27 (p=0.001) and 0.96 (p=0.9), respectively. For pelvic SPC no increase was observed (sHR=0.8, p=0.4). Compared to the general population, IMRT was associated with significantly increased risks for non-pelvic SPC in the 50–69 year age group (SIR=1.90, p<0.05) but not in the 70–79 years group (SIR=1.08).

Conclusion

IMRT is associated with increased SPC risks for subjects who are relatively young at time of treatment. Additional research on aspects of IMRT that may cause this effect is essential to minimize risks for future patients receiving modern radiotherapy.

An overview of patients with urothelial bladder cancer over the past two decades: a Surveillance, Epidemiology, and End Results (SEER) study

Background

To explore the overall trends of incidence rate (IR), mortality and survival outcomes of patients with urothelial bladder cancer (UBC) over the past two decades.

Methods

Patients diagnosed with UBC from 1993 to 2012 were extracted from the Surveillance, Epidemiology and End Result (SEER) 18 database. Baseline characteristics and treatment types of included patients were collected retrospectively. Moreover, the age-adjusted IRs and annual percent changes (APCs) were obtained. Afterwards, we calculated the standardized mortality ratios (SMRs) for bladder cancer (BC), cardiovascular disease (CVD) and all-cause mortality by comparing UBC cases with the general population. Finally, survival outcomes of UBC patients were analyzed and compared.

Results

A total of 220,405 UBC patients were identified, including 167,036 (75.79%) male patients and 53,369 (24.21%) female patients, with an average age of 70.84 years old. Most patients were White (89.85%), with older age (71.67%, >65 years old), lower T stage diseases (78.11%, < T2) and lower median household income (55.37%). When compared with patients diagnosed between 1993 and 2002, those diagnosed between 2003 and 2012 had older age (mean: 71.15 vs. 70.16 years old, P<0.001), higher proportion of men (76.22% vs. 74.83%, P<0.001) and lower median household income (56.69% vs. 52.50%, P<0.01). Overall, the IR of UBC increased slightly before 2003 and maintained a stable trend of about 20 per 100,000 person-years after 2003. Additionally, CVD was recognized as an important cause of death (COD) of UBC patients. UBC patients were 44.5 times more likely to die of CVD when compared with the general population. Furthermore, the 3-, 5- and 10-year overall survival (OS) and cancer-specific survival (CSS) rates were 0.709, 0.609 and 0.421, and 0.861, 0.831 and 0.789, respectively. Finally, survival outcomes between patients diagnosed in the two periods (1993–2002 vs. 2003–2012) were not significantly different.

Conclusions

The IR of UBC increased slightly before 2003 and remained stable after 2003. UBC patients had higher CVD burden than the general population. Hence, cardiovascular health should be emphasized to reduce mortality after UBC diagnosis. Lastly, survival outcomes of UBC patients in the last two decades showed no significant difference.

Risk of subsequent primary cancers after carbon ion radiotherapy, photon radiotherapy, or surgery for localised prostate cancer: a propensity score-weighted, retrospective, cohort study

BACKGROUND

The risk of subsequent primary cancers in patients with prostate cancer after treatment with photon radiotherapy is small in absolute numbers, but it is higher than that after surgical treatment. Carbon ion radiotherapy has a theoretically lower risk of inducing secondary malignancies than photon radiotherapy, but this risk has not been investigated in practice because of the low number of facilities offering such therapy worldwide and the limited data on long-term follow-up because the therapy has only been available since 1994. We aimed to analyse the risk of subsequent primary cancers after treatment with carbon ion radiotherapy in patients with localised prostate cancer and to compare it with that after photon radiotherapy or surgery in this setting.

METHODS

In this retrospective cohort study, we reviewed records of patients who received carbon ion radiotherapy for prostate cancer between June 27, 1995, and July 10, 2012, at the National Institute of Radiological Sciences (NIRS) in Japan. We also retrieved the records of patients diagnosed and treated for prostate cancer between Jan 1, 1994, and Dec 31, 2012, from the Osaka Cancer Registry. Eligible patients had histologically confirmed localised prostate cancer and a minimum follow-up of at least 3 months; no age restrictions were applied. We excluded patients with metastasis, node-positive disease, or locally invasive (T4 stage) prostate cancer, those with previous or synchronous malignancies, and those who received previous radiotherapy or chemotherapy. We did a multivariable analysis to estimate predictors of subsequent cancers after carbon ion radiotherapy treatment. We also used propensity score inverse probability weighting to retrospectively compare the incidence of subsequent cancers in patients with localised prostate cancer treated with carbon beams, photon radiotherapy, or surgery.

FINDINGS

Of 1580 patients who received carbon radiotherapy for prostate cancer at the NIRS, 1455 (92%) patients met the eligibility criteria. Of 38 594 patients with prostate cancer identified in the Osaka registry, 1983 (5%) patients treated with photon radiotherapy and 5948 (15%) treated with surgery were included. Median follow-up durations were 7·9 years (IQR 5·9-10·0) for patients who received carbon ion radiotherapy (after limiting the database to 10-year maximum follow-up), 5·7 years (4·5-6·4) for patients who received photon radiotherapy, and 6·0 years (5·0-8·6) for those who received surgery. 234 subsequent primary cancers were diagnosed in the carbon ion radiotherapy cohort; some patients developed several tumours. On multivariable analysis, age (p=0·0021 for 71-75 years vs ≤60 years; p=0·012 for >75 years vs ≤60 years) and smoking (p=0·0005) were associated with a higher risk of subsequent primary cancers in patients treated with carbon ion radiotherapy. In the propensity score-weighted analyses, carbon ion radiotherapy was associated with a lower risk of subsequent primary cancers than photon radiotherapy (hazard ratio [HR] 0·81 [95% CI 0·66-0·99]; p=0·038) or surgery (HR 0·80 [0·68-0·95]; p=0·0088), whereas photon radiotherapy was associated with a higher risk of subsequent primary cancers than surgery (HR 1·18 [1·02-1·36]; p=0·029).

INTERPRETATION

Our analysis suggests that patients with localised prostate cancer treated with carbon ion radiotherapy appear to have a lower risk of subsequent primary cancers than those treated with photon radiotherapy. Although prospective evaluation with longer follow-up is warranted to support these results, our data supports a wider adoption of carbon ion radiotherapy for patients with expected long-term overall survival or those with poor outcomes after receiving conventional treatments.

FUNDING

Research Project for Heavy Ions at the National Institute of Radiological Sciences (Japan).

High prevalence of secondary bladder cancer in men on radiotherapy for prostate cancer: evidence from a meta-analysis

Objective

To assess whether radiotherapy (RT) for prostate cancer (PCa) was a risk factor for secondary bladder cancer (BLCa) through a meta-analysis.

Materials and methods

The MEDLINE, Embase, and the Cochrane Library were systematically searched for all studies investigating the risk of BLCa in patients with RT. The association between RT and risk of BLCa was summarized using hazard ratio with a 95%CI. The protocol for this meta-analysis is available from PROSPERO (CRD42018090075).

Results

Overall, 619,479 participants (age: 57-79 years) were included from 15 studies, 206,852 of whom were patients who received RT. Synthesis of results indicated that RT was significantly associated with an increased risk of BLCa compared with the risk in those who received radical prostatectomy or non-RT (overall HR=1.6, 95%CI: 1.33-1.92, P<0.001). The results were consistent when restricted to a 5-year lag period (HR=1.84, 95%CI: 1.26-2.69, P=0.002) and multivariable adjustment (HR=1.96, 95%CI: 1.47-2.62, P<0.001), but not for 10-year lag period (HR=1.93, 95%CI: 0.9- 4.16, P=0.093) and brachytherapy subgroup (HR=1.33, 95%CI: 0.87-2.05, P=0.188). The GRADE-profiler revealed that the rate of events of BLCa on average in the RT-patients and the non-RT control was 2,462/183,669 (1.3%) and 4,263/382,761(1.1%), respectively; the overall quality of the evidence was low.

Conclusion

Patients who received RT for PCa was associated with higher risks of developing secondary BLCa compared to those unexposed to RT, but the absolute effect was low.

Pattern of solid and hematopoietic second malignancy after local therapy for prostate cancer

BACKGROUND AND PURPOSE

Second malignancies (SM) after external beam radiotherapy (EBRT) or brachytherapy (BT) for prostate cancer (PCa) are rare but serious sequelae.

MATERIALS AND METHODS

The Surveillance, Epidemiology, and End Results (SEER) database was used to identify men diagnosed with cT1-2N0M0 PCa between 1999 and 2005, who underwent EBRT, BT or radical prostatectomy (RP). Patients with time interval to second malignancy or follow-up shorter than five and two years were excluded for solid and hematopoietic SM analyses respectively. Risks for solid and hematopoietic SM were evaluated via the multivariate Fine and Gray proportional hazards model.

RESULTS

EBRT and BT resulted in similar increases in solid and hematopoietic SM compared to RP. In subgroup analysis stratified by treatment modality, only the EBRT cohort demonstrated significantly decreased solid and hematopoietic SM in years 2002-2005 compared to years 1999-2001, with adjusted-hazard ratios of 0.752 (p=0.001) and 0.815 (p=0.018) respectively.

CONCLUSIONS

EBRT and BT resulted in statistically equivalent increase in both solid and hematopoietic SM compared to RP. EBRT in more recent years resulted in significantly decreased solid and hematopoietic SM, coinciding with increased utilization of IMRT.