Reducing Bias in Oncology Research: The End of the Radiation Variable in the Surveillance, Epidemiology, and End Results (SEER) Program

Surveillance, Epidemiology, and End Results database and propensity score matching analysis of postoperative radiotherapy for non-malignant meningioma: A retrospective cohort study

BACKGROUND

The clinical effect of postoperative radiotherapy (PORT) in non-malignant meningioma (NMM) has not been well explored.

METHODS

A total of 8629 patients with NMM (surgery alone group: n = 7716, postoperative radiotherapy group: n = 913) were obtained from the Surveillance, Epidemiology, and End Results database. Patient profiles were matched by 1:1 propensity score matching (PSM). Logistic regression analysis was performed to identify factors associated with PORT versus surgery alone (SA). Univariate and multivariate Cox regression analyses determined prognostic variables with overall survival (OS) in NMM. Subgroup analyses were performed with Cox proportional hazards regression models.

RESULTS

All the SA (n = 7716) and PORT (n = 913) groups were included. Women with PORT (66.3%) and SA (70.9%) were almost twice as likely as men, and tumors with benign behaviors in the SA group were almost seven times more frequent than those with malignant characteristics. We explored the demographic, clinical characteristics, and prognostic factors in NMM. Laterality, surgery, tumor size, diagnosis year, age, and tumor behavior were associated with PORT versus SA. Patients treated with PORT had better OS than those treated with SA (p = 0.03). After PSM, PORT remained comparable to SA (hazard ratio 0.56, 95% confidence interval 0.35-0.88, p = 0.013). In the subgroup analysis of PORT treatment, borderline malignant behavior increased the death risk by 23%, while other variables did not have a significant clinical benefit (p > 0.05).

CONCLUSIONS

Borderline malignant behavior should be considered seriously, and the PORT regimen should be actively implemented for patients with benign meningiomas.

Is the Number of National Database Research Studies in Musculoskeletal Sarcoma Increasing, and Are These Studies Reliable?

BACKGROUND

Large national databases have become a common source of information on patterns of cancer care in the United States, particularly for low-incidence diseases such as sarcoma. Although aggregating information from many hospitals can achieve statistical power, this may come at a cost when complex variables must be abstracted from the medical record. There is a current lack of understanding of the frequency of use of the Surveillance, Epidemiology, and End Results (SEER) database and the National Cancer Database (NCDB) over the last two decades in musculoskeletal sarcoma research and whether their use tends to produce papers with conflicting findings.

QUESTIONS/PURPOSES

(1) Is the number of published studies using the SEER and NCDB databases in musculoskeletal sarcoma research increasing over time? (2) What are the author, journal, and content characteristics of these studies? (3) Do studies using the SEER and the NCDB databases for similar diagnoses and study questions report concordant or discordant key findings? (4) Are the administrative data reported by our institution to the SEER and the NCDB databases concordant with the data in our longitudinally maintained, physician-run orthopaedic oncology dataset?

METHODS

To answer our first three questions, PubMed was searched from 2001 through 2020 for all studies using the SEER or the NCDB databases to evaluate sarcoma. Studies were excluded from the review if they did not use these databases or studied anatomic locations other than the extremities, nonretroperitoneal pelvis, trunk, chest wall, or spine. To answer our first question, the number of SEER and NCDB studies were counted by year. The publication rate over the 20-year span was assessed with simple linear regression modeling. The difference in the mean number of studies between 5-year intervals (2001-2005, 2006-2010, 2011-2015, 2016-2020) was also assessed with Student t-tests. To answer our second question, we recorded and summarized descriptive data regarding author, journal, and content for these studies. To answer our third question, we grouped all studies by diagnosis, and then identified studies that shared the same diagnosis and a similar major study question with at least one other study. We then categorized study questions (and their associated studies) as having concordant findings, discordant findings, or mixed findings. Proportions of studies with concordant, discordant, or mixed findings were compared. To answer our fourth question, a coding audit was performed assessing the concordance of nationally reported administrative data from our institution with data from our longitudinally maintained, physician-run orthopaedic oncology dataset in a series of patients during the past 3 years. Our orthopaedic oncology dataset is maintained on a weekly basis by the senior author who manually records data directly from the medical record and sarcoma tumor board consensus notes; this dataset served as the gold standard for data comparison. We compared date of birth, surgery date, margin status, tumor size, clinical stage, and adjuvant treatment.

RESULTS

The number of musculoskeletal sarcoma studies using the SEER and the NCDB databases has steadily increased over time in a linear regression model (β = 2.51; p < 0.001). The mean number of studies per year more than tripled during 2016-2020 compared with 2011-2015 (39 versus 13 studies; mean difference 26 ± 11; p = 0.03). Of the 299 studies in total, 56% (168 of 299) have been published since 2018. Nineteen institutions published more than five studies, and the most studies from one institution was 13. Orthopaedic surgeons authored 35% (104 of 299) of studies, and medical oncology journals published 44% (130 of 299). Of the 94 studies (31% of total [94 of 299]) that shared a major study question with at least one other study, 35% (33 of 94) reported discordant key findings, 29% (27 of 94) reported mixed key findings, and 44% (41 of 94) reported concordant key findings. Both concordant and discordant groups included papers on prognostic factors, demographic factors, and treatment strategies. When we compared nationally reported administrative data from our institution with our orthopaedic oncology dataset, we found clinically important discrepancies in adjuvant treatment (19% [15 of 77]), tumor size (21% [16 of 77]), surgery date (23% [18 of 77]), surgical margins (38% [29 of 77]), and clinical stage (77% [59 of 77]).

CONCLUSION

Appropriate use of databases in musculoskeletal cancer research is essential to promote clear interpretation of findings, as almost two-thirds of studies we evaluated that asked similar study questions produced discordant or mixed key findings. Readers should be mindful of the differences in what each database seeks to convey because asking the same questions of different databases may result in different answers depending on what information each database captures. Likewise, differences in how studies determine which patients to include or exclude, how they handle missing data, and what they choose to emphasize may result in different messages getting drawn from large-database studies. Still, given the rarity and heterogeneity of sarcomas, these databases remain particularly useful in musculoskeletal cancer research for nationwide incidence estimations, risk factor/prognostic factor assessment, patient demographic and hospital-level variable assessment, patterns of care over time, and hypothesis generation for future prospective studies.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Outcome of limited-stage peripheral T-Cell lymphoma after CHOP(-like) therapy: A population based study of 239 patients from the Nordic lymphoma epidemiology group

Peripheral T-Cell Lymphomas (PTCLs) are rare, aggressive lymphomas with poor outcomes, but limited-stage disease is infrequent and not well-described. This study reports outcomes and prognostic factors in limited-stage nodal PTCLs in a binational population-based setting. Patients were identified from the Danish and Swedish lymphoma registries. Adults diagnosed with limited-stage nodal PTCL (stage I-II) and treated with CHOP(-like) therapy ±radiotherapy between 2000 and 2014 were included. Medical records were reviewed by local investigators. A total of 239 patients with a median age of 62 years were included; 67% received 6-8 cycles of CHOP(-like) therapy and 22% received 3-4 cycles, of which 59% also received radiotherapy. Autologous stem cell transplant consolidation was administered to 16% of all patients. Median follow-up was 127 months with 5-years overall survival (OS) of 58% (95% CI: 53-65) and progression-free survival (PFS) of 53% (95% CI: 47-59). In multivariable analysis, age ≥ 60 years and B-symptoms were unfavorable and ALK+ anaplastic large cell T-Cell lymphoma was favorable for survival outcomes. There was no difference in treatment-specific outcome (3-4 cycles vs. 6-8 cycles of CHOP(-like) ± radiotherapy). Low-risk patients (age < 60 without B-symptoms) had a 5-year OS of 77% (95% CI 67-89%). In the present study of limited-stage nodal PTCL, survival after curative intent chemotherapy +/- radiotherapy was inferior to that of limited-stage diffuse large B-cell lymphoma, but a subgroup of young patients without B-symptoms had very good outcomes. Treatment outcomes after 3-4 cycles versus 6-8 cycles of CHOP(-like) therapy were comparable.

Prevalence of Missing Data in the National Cancer Database and Association With Overall Survival

IMPORTANCE

Cancer registries are important real-world data sources consisting of data abstraction from the medical record; however, patients with unknown or missing data are underrepresented in studies that use such data sources.

OBJECTIVE

To assess the prevalence of missing data and its association with overall survival among patients with cancer.

DESIGN, SETTING, AND PARTICIPANTS

In this retrospective cohort study, all variables within the National Cancer Database were reviewed for missing or unknown values for patients with the 3 most common cancers in the US who received diagnoses from January 1, 2006, to December 31, 2015. The prevalence of patient records with missing data and the association with overall survival were assessed. Data analysis was performed from February to August 2020.

EXPOSURES

Any missing data field within a patient record among 63 variables of interest from more than 130 total variables in the National Cancer Database.

MAIN OUTCOMES AND MEASURES

Prevalence of missing data in the medical records of patients with cancer and associated 2-year overall survival.

RESULTS

A total of 1 198 749 patients with non-small cell lung cancer (mean [SD] age, 68.5 [10.9] years; 628 811 men [52.5%]), 2 120 775 patients with breast cancer (mean [SD] age, 61.0 [13.3] years; 2 101 758 women [99.1%]), and 1 158 635 patients with prostate cancer (mean [SD] age, 65.2 [9.0] years; 100% men) were included in the analysis. Among those with non-small cell lung cancer, 851 295 patients (71.0%) were missing data for variables of interest; 2-year overall survival was 33.2% for patients with missing data and 51.6% for patients with complete data (P < .001). Among those with breast cancer, 1 161 096 patients (54.7%) were missing data for variables of interest; 2-year overall survival was 93.2% for patients with missing data and 93.9% for patients with complete data (P < .001). Among those with prostate cancer, 460 167 patients (39.7%) were missing data for variables of interest; 2-year overall survival was 91.0% for patients with missing data and 95.6% for patients with complete data (P < .001).

CONCLUSIONS AND RELEVANCE

This study found that within a large cancer registry-based real-world data source, there was a high prevalence of missing data that were unable to be ascertained from the medical record. The prevalence of missing data among patients with cancer was associated with heterogeneous differences in overall survival. Improvements in documentation and data quality are necessary to make optimal use of real-world data for clinical advancements.

Treatment selection and survival outcomes in Early-Stage peripheral T-Cell lymphomas: does anaplastic lymphoma kinase mutation impact the benefit of consolidative radiotherapy?

The role of consolidative radiotherapy (RT) is less substantiated in uncommon peripheral T-cell lymphomas (PTCLs). Anaplastic lymphoma kinase (ALK) mutation sub-categorizes PTCLs, with ALK (+) having a distinctly favorable prognosis. We aimed to use the National Cancer Database to examine the potential role of RT in PTCLs and if ALK mutation can be used to predict the benefit of consolidative RT after multi-agent chemotherapy (combined modality therapy). We identified 3670 stage I-II PTCL patients treated with multi-agent chemotherapy alone or combined modality therapy (CMT) between 1998-2012. After adjusting for immortal-time and indication bias, CMT was associated with better OS than multi-agent chemotherapy alone for ALK (-) patients (HR 0.69, 95% CI 0.52-0.92, p = .01); no significant difference was noted for ALK (+) (HR 1.03, 95% CI 0.75-1.41, p = .85). CMT is associated with improved OS for ALK (-) PTCLs; while no such benefit was seen for the ALK (+) subgroup.

Radiation Records in the National Cancer Database: Variations in Coding and/or Practice Can Significantly Alter Survival Results

PURPOSE

The aim of the current work was to quantify internally inconsistent and anomalous radiation therapy (RT) data in the National Cancer Database (NCDB) and determine their association with overall survival (OS) using node-positive uterine cancer as a test clinical scenario.

MATERIALS AND METHODS

We identified all NCDB participants with International Federation of Gynecology and Obstetrics stage IIIC1 to IIIC2 uterine cancer treated with hysterectomy and adjuvant RT between 1998 and 2012. Variables that were reviewed to identify anomalous data included RT site, modality, dose, fractions, timing, duration, and stage. We used χ² testing to associate anomalous data with reporting facility and demographic variables. OS was estimated using the Kaplan-Meier method and comparison between cohorts was performed using the log-rank test. Univariable and multivariable Cox proportional hazards regression analyses were performed.

RESULTS

Of the 14,298 analyzed participants, 2,288 (16.0%) had one or more anomalous data entry, 538 (3.8%) likely because of an incomplete RT course. χ² testing suggested differences in anomalous data prevalence by reporting facility type (P = .0007), geographic region (P < .001), distance from participants' homes (P < .001), diagnosis year (P < .001), and location of RT relative to reporting facility (P = .0038). Five-year OS in those with one or more anomalous data entry was 51.3% versus 58.0% for those without anomalous data (P < .001), and anomalous data remained significantly associated with OS on multivariable analysis. After excluding insufficient, excessive, or unknown total RT dose, anomalous data were no longer significant on multivariable analysis.

CONCLUSION

The overwhelming majority of RT data within the NCDB seem to be appropriate for the clinical scenario. Nevertheless, approximately one eighth of participants in this test clinical scenario had adjuvant RT data that were internally inconsistent or outside generously defined norms. The presence of anomalous RT data was significantly associated with compromised OS, an effect not observed after correcting for total RT dose.

Association between Long-Term Second Malignancy Risk and Radiation: A Comprehensive Analysis of the Entire Surveillance, Epidemiology, and End Results Database (1973-2014)

Purpose

Second malignancies (SMs) after radiation therapy are rare but serious sequelae of treatment. This study investigates whether radiation therapy use is associated with changes in baseline SM risk.

Methods and Materials

We extracted all patients with cancer, with or without SM, in the Surveillance, Epidemiology, and End Results database from 1973 to 2014. Cumulative incidence of SM for patients stratified by radiation therapy status was calculated using a competing risk model, both for the entire cohort and for subgroups based on the primary tumor's anatomic location.

Results

We identified 2,872,063 patients with cancer, including 761,289 patients who received radiation therapy and 2,110,774 who did not. The SM rate at 20 years for patients receiving radiation therapy versus no radiation therapy was 21.4% versus 18.8%. The relative risk for SM associated with radiation therapy for the overall group was 1.138 at 20 years. The relative risks for SM associated with radiation therapy to malignancies arising from central nervous system and orbits, head and neck, thorax, abdomen, and pelvis at 20 years were 0.704, 1.011, 0.559, 0.646, and 1.106 for men and 0.792, 1.298, 1.265, 0.780, and 0.988 for women, respectively.

Conclusions

The association between SM and radiation therapy varies with both sex and disease anatomic location, with the largest increase in SM seen in females irradiated to the head and neck region. Overall, the absolute change in SM rates associated with radiation therapy remains small, with differences in various clinical contexts.

The impact of age at the time of radiotherapy for localized prostate cancer on the development of second primary malignancies

PURPOSE

There is a known increased risk of second primary malignancy (SPM) in patients with prostate cancer (CaP) treated with radiotherapy (RT). It is unclear how age at diagnosis influences the risk of SPMs.

MATERIALS AND METHODS

Using the 1973 to 2013 Surveillance, Epidemiology, and End Results Program, we studied the impact of age on SPMs (defined as a bladder or rectal tumor) after localized CaP treatment with radical prostatectomy (RP) or RT. SPM risk was compared using inverse probability of treatment weighting (IPTW)-adjusted cumulative incidence function and competing-risk proportional hazard models. Overall survival (OS) in patients with SPM was compared using Kaplan Meier and Cox regression analyses.

RESULTS

A total of 579,608 patients met inclusion criteria, and 51.8% of the cohort was treated with RT. The 10- and 20-year cumulative incidences of competing risk (IPTW adjusted) of SPMs were 1.9% (95%CI = 1.8-1.9%) and 3.6% (95%CI = 3.4-3.7%) after RP vs. 2.7% (95%CI = 2.6-2.8%) and 5.4%(95%CI = 5.3-5.6%) after RT. IPTW-adjusted competing risk hazard ratio (HR) of SPM after RT compared to RP was increased in the entire cohort (HR 1.46; 95%CI = 1.39-1.53, P < 0.001) and was highest in the youngest patients: Age <55 HR = 1.83 (95% confidence interval [CI] = 1.49-2.24, P<0.001), Age 55 to 64 HR = 1.66 (95%CI = 1.54-1.79, P < 0.001), Age 65-74 HR = 1.41 (95%CI = 1.33-1.48, P < 0.001), Age ≥75 HR = 1.14 (95%CI = 0.97-1.35, P = 0.112). At 10 years, SPM-specific mortality occurred in 28.9% of patients treated with RT, though OS with SPM was worse in the youngest patients: Age <55 HR = 1.88 (95%CI = 1.25-2.81, P = 0.002), Age 55-64 HR = 1.60 (95%CI = 1.42-1.81, P < 0.001), Age 65-74 HR = 1.40 (95%CI = 1.30-1.52, P < 0.001), Age ≥ 75 HR = 1.27 (95%CI = 1.06-1.53, P = 0.009). All of the age categories had similar median follow-up times.

CONCLUSION

At 10 years there is a 1.8% increased incidence of SPM after RT compared to RP, of which <30% of RT-treated patients with an SPM die as a result of a SPM. However, the risk of SPMs was greatest among younger men treated with RT for localized CaP, and this relationship could not be explained solely by follow-up time, latency time, or life expectancy. An improved understanding of those at the highest risk of SPMs may help tailor treatment and surveillance strategies.

Limb-sparing surgery plus radiotherapy results in superior survival: an analysis of patients with high-grade, extremity soft-tissue sarcoma from the NCDB and SEER

Small randomized trials have not shown an overall survival (OS) difference among local treatment modalities for patients with extremity soft‐tissue sarcomas (E‐STS) but were underpowered for OS. We examine the impact of local treatment modalities on OS and sarcoma mortality (SM) using two national registries. The National Cancer Database (NCDB) and the Surveillance, Epidemiology, and End Results (SEER) Program were analyzed separately to identify patients with stage II‐III, high‐grade E‐STS diagnosed between 2004 and 2013 and treated with (1) amputation alone, (2) limb‐sparing surgery (LSS) alone, (3) preoperative radiation therapy (RT) and LSS, or (4) LSS and postoperative RT. Multivariable analyses (MVAs) and 1:1 matched pair analyses (MPAs) examined treatment impacts on OS (both databases) and SM (SEER only). From the NCDB and SEER, 7828 and 2937 patients were included. On MVAs, amputation was associated with inferior OS and SM. Relative to LSS alone, both preoperative RT and LSS (HR, 0.70; 95% CI: 0.62‐0.78) and LSS and postoperative RT (HR, 0.69; 95% CI: 0.63‐0.75) improved OS in NCDB analyses with confirmation by SEER. Estimated median survivals from MPA utilizing NCDB data were 7.2 years with LSS alone (95% CI: 6.5‐8.9 years) vs 9.8 years (95% CI: 9.0‐11.2 years) with LSS and postoperative RT. A MPA comparing preoperative RT and LSS to LSS alone found median survivals of 8.9 years (95% CI: 7.9‐not estimable) and 6.6 years (95% CI: 5.4‐7.8 years). Optimal high‐grade E‐STS management includes LSS with preoperative or postoperative RT as evidenced by superior OS and SM.

Health Care Disparities in Cancer Patients Receiving Radiation: Changes in Insurance Status After Medicaid Expansion Under the Affordable Care Act

PURPOSE

To compare insurance status in cancer patients receiving radiation before and after Medicaid expansion under the Patient Protection and Affordable Care Act (ACA), in both expanded and non-expanded states.

METHODS AND MATERIALS

Newly diagnosed cancer patients aged 18 to 64 years who received radiation from 2011 to 2014 were compiled from the Surveillance, Epidemiology, and End Results database. Patients with a prior cancer diagnosis or unknown insurance status were excluded. Insurance rates at diagnosis were examined before (2011-2013) and after Medicaid expansion (2014) and compared between states that fully or did not fully expand Medicaid.

RESULTS

A total of 197,290 patients were analyzed. Of these, 73% lived in expanded states. After expansion, there was a 53% relative decrease in uninsured rates in expanded states (4.3%-2.1%) and a 5% relative decrease in non-expanded states (8.4%-8.0%) (P < .0001). In expanded states, the uninsured rate decreased regardless of race (whites: relative decrease 56%, 4.3% to 1.9%; blacks: relative decrease 50%, 6.0 to 3.0%; both P < .0001) or county poverty level (low poverty: relative decrease 46%, 3.9% to 2.1%; high poverty: relative decrease 60%, 4.5% to 1.8%; both P < .0001). In non-expanded states, a decrease in uninsured levels was seen primarily in whites (relative decrease 9%, 7.8% to 7.1%, P < .0001; blacks: relative increase 7%, 9.9% to 10.6%, P = .37) and those living in areas with the lowest poverty (relative decrease 27%, 4.8% to 3.5%, P = .04; high poverty: relative increase 2%, 10.9% to 11.1%, P = .17). Blacks and those living in the highest poverty areas had the greatest level of benefit from full expansion (absolute benefit 2.0%-2.3%, P = .0093 and P = .0029, respectively).

CONCLUSIONS

Medicaid expansion in 2014 significantly decreased uninsured rates for cancer patients receiving radiation. Full expansion decreased rates of uninsurance to a greater degree and seemed to decrease racial and economic disparities.