Immortal Time Bias in National Cancer Database Studies

Newman, N.B.; Brett, C.; Kluwe, Christien; Patel, Chirayu G.; Attia, Albert; Osmundson, Evan C.; Kachnic, Lisa A.

doi:10.1016/j.ijrobp.2019.07.056

Cited by 26 publications

(18 citation statements)

References 75 publications

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“…There are several ways of calculating survival in different study designs. Recently, much attention has been paid to immortal time bias, i.e., the time between diagnosis and the initiation of cancer treatment, which researchers should be aware of to avoid misleading conclusions concerning the benefits of therapy (30)(31)(32)(33). For example, in the South Korean study with hilar cholangiocarcinoma (12), survival was calculated from the date of cancer diagnosis to death or the last follow-up.…”

Section: Discussionmentioning

confidence: 99%

Chemotherapy Improves Survival After Percutaneous Biliary Drainage in Patients With Pancreatic or Biliary Tract Cancer With Biliary Obstruction

Niemelä¹,

Syrjälä²,

Ohtonen³

et al. 2021

Anticancer Res

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Background: The survival benefit of chemotherapy compared to best supportive care (BSC) after percutaneous transhepatic biliary drainage (PTBD) was evaluated in patients with pancreatic or biliary tract cancer. Patients and Methods: A retrospective registry study was conducted at a tertiary-level university hospital. The endpoint was survival measured from the PTBD and the initiation of chemotherapy. Results: Among 158 patients (mean age=74 years, range=43-93 years; 51.9% women), 82 (51.9%) had pancreatic cancer and 76 (48.1%) had biliary tract cancer. After PTBD, 32 (20.3%) patients received chemotherapy and had a median survival of 11.7 months; 126 (79.7%) patients received only BSC resulting in a median survival of 1.7 months. The hazard ratio for survival at 1 year for patients who received chemotherapy compared to BSC was 0.22 (95% confidence interval=0.12-0.41, p<0.001). Conclusion: After PTBD, patients with pancreatic or biliary tract cancer should be critically evaluated by an oncologist to determine whether chemotherapy is possible, as it seems to significantly improve survival compared to BSC.

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Section: Discussionmentioning

confidence: 99%

Chemotherapy Improves Survival After Percutaneous Biliary Drainage in Patients With Pancreatic or Biliary Tract Cancer With Biliary Obstruction

Niemelä¹,

Syrjälä²,

Ohtonen³

et al. 2021

Anticancer Res

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“…Hazard ratios (HRs) with 95% confidence intervals (95% CI) for possible significant prognostic factors and treatment options were calculated using univariable Cox regression. Time-dependent multivariable adjusted Cox regression model was used to preclude the immortal-time bias considering treatment options [ 16 , 17 ]. Due to missing data on some of the risk factors, a multiple imputation technique was used to increase the precision and reduce bias in the analyses.…”

Section: Methodsmentioning

confidence: 99%

Nephrectomy improves the survival of metastatic renal cell cancer patients with moderate to good performance status—results from a Finnish nation-wide population-based study from 2005 to 2010

et al. 2021

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Background The purpose of this study was to evaluate the effects of cytoreductive nephrectomy (CN) and metastasectomies on the survival of patients with synchronous metastatic renal cell cancer (mRCC) using real-life, population-based national dataset. Methods Nationwide data, including all cases of synchronous mRCC in Finland diagnosed on a 6-year timeframe, based on the Finnish Cancer Registry and complemented with patient records from the treating hospitals, were analyzed. Patients with Eastern Cooperative Oncology Group (ECOG) performance status 3–4 were excluded. Univariate and adjusted multivariable survival analysis were performed, including subgroup analysis for patients with different medical therapies. Nephrectomy complications were also analyzed. Results A total of 732 patients were included in the analysis. CN was performed for 389 (53.1%) patients, whereas 68 (9.3%) patients underwent nephrectomy and metastasectomies of all lesions (surgery with curative intent). Median overall survival (OS) for patients who did not undergo nephrectomy was 5.9 (95% confidence interval [CI] = 4.6–7.2) months. Patients who had a CN had a median OS of 16.6 (95% CI = 14.2–19.1, p < 0.001) months, whereas patients who had surgery with curative intent had a median OS of 51.3 (95% CI = 36.0–66.6, p < 0.001) months. The survival benefit of CN and metastasectomies remained significant in all medical therapy subgroups and in both of the applied multivariable statistical models. Conclusions Surgical treatment of metastatic renal cell cancer is associated with a significant survival benefit in patients with good and moderate performance status, regardless of the chosen medical therapy.

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“…To adjust for immortal time bias, we employed a single landmark time and excluded patients with fewer than 3 months of follow-up. 14 We chose this time period as it is our experience that the vast majority of patients complete adjuvant RT within 3 months of surgery.…”

Section: Methodsmentioning

confidence: 99%

“…Kaplan‐Meier and multivariate Cox proportional hazards analyses were used to compare overall survival (OS) between patients who did or did not receive adjuvant RT. To adjust for immortal time bias, we employed a single landmark time and excluded patients with fewer than 3 months of follow‐up 14 . We chose this time period as it is our experience that the vast majority of patients complete adjuvant RT within 3 months of surgery.…”

Section: Methodsmentioning

confidence: 99%

Comparing national practice versus standard guidelines for the use of adjuvant treatment following robotic surgery for oropharyngeal squamous cell carcinoma

et al. 2020

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Background Recent historical management of oropharyngeal squamous cell carcinoma typically includes radiotherapy with/without chemotherapy. Novel surgical techniques such as robotic surgery have made primary surgery more frequent; however, postoperative radiotherapy may be recommended. We aimed to assess adherence to guidelines for postoperative therapy following robotic surgery. Methods Using the National Cancer Database, we analyzed the frequency of radiotherapy following robotic surgery for cT1‐3cN0‐2cM0 squamous cell carcinoma of the oropharynx, specifically in the presence of widely accepted indications for postoperative radiotherapy and/or chemotherapy. Results Approximately two‐thirds of patients received radiotherapy after robotic surgery for early‐intermediate stage oropharyngeal cancer. One in five patients with an indication for adjuvant radiotherapy and 1/3 with an indication for adjuvant chemotherapy did not receive recommended adjuvant therapy. Conclusions A high proportion of patients require radiotherapy after robotic surgery for early‐intermediate stage oropharyngeal cancer. Patients with an indication for further adjuvant therapy commonly do not receive it.

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Immortal Time Bias in National Cancer Database Studies

Cited by 26 publications

References 75 publications

Chemotherapy Improves Survival After Percutaneous Biliary Drainage in Patients With Pancreatic or Biliary Tract Cancer With Biliary Obstruction

Chemotherapy Improves Survival After Percutaneous Biliary Drainage in Patients With Pancreatic or Biliary Tract Cancer With Biliary Obstruction

Nephrectomy improves the survival of metastatic renal cell cancer patients with moderate to good performance status—results from a Finnish nation-wide population-based study from 2005 to 2010

Comparing national practice versus standard guidelines for the use of adjuvant treatment following robotic surgery for oropharyngeal squamous cell carcinoma

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