Challenges of Guarantee-Time Bias GIOBBIE-HURDER, Anita; GELBER, Richard D; REGAN, Meredith M
Journal of clinical oncology,
08/2013, Volume:
31, Issue:
23
Journal Article
Peer reviewed
Open access
The potential for guarantee-time bias (GTB), also known as immortal time bias, exists whenever an analysis that is timed from enrollment or random assignment, such as disease-free or overall ...survival, is compared across groups defined by a classifying event occurring sometime during follow-up. The types of events associated with GTB are varied and may include the occurrence of objective disease response, onset of toxicity, or seroconversion. However, comparative analyses using these types of events as predictors are different from analyses using baseline characteristics that are specified completely before the occurrence of any outcome event. Recognizing the potential for GTB is not always straightforward, and it can be challenging to know when GTB is influencing the results of an analysis. This article defines GTB, provides examples of GTB from several published articles, and discusses three analytic techniques that can be used to remove the bias: conditional landmark analysis, extended Cox model, and inverse probability weighting. The strengths and limitations of each technique are presented. As an example, we explore the effect of bisphosphonate use on disease-free survival (DFS) using data from the BIG (Breast International Group) 1-98 randomized clinical trial. An analysis using a naive approach showed substantial benefit for patients who received bisphosphonate therapy. In contrast, analyses using the three methods known to remove GTB showed no statistical evidence of a reduction in risk of a DFS event with bisphosphonate therapy.
To update key recommendations of the American Society of Clinical Oncology/College of American Pathologists estrogen (ER) and progesterone receptor (PgR) testing in breast cancer guideline.
A ...multidisciplinary international Expert Panel was convened to update the clinical practice guideline recommendations informed by a systematic review of the medical literature.
The Expert Panel continues to recommend ER testing of invasive breast cancers by validated immunohistochemistry as the standard for predicting which patients may benefit from endocrine therapy, and no other assays are recommended for this purpose. Breast cancer samples with 1% to 100% of tumor nuclei positive should be interpreted as ER positive. However, the Expert Panel acknowledges that there are limited data on endocrine therapy benefit for cancers with 1% to 10% of cells staining ER positive. Samples with these results should be reported using a new reporting category, ER Low Positive, with a recommended comment. A sample is considered ER negative if < 1% or 0% of tumor cell nuclei are immunoreactive. Additional strategies recommended to promote optimal performance, interpretation, and reporting of cases with an initial low to no ER staining result include establishing a laboratory-specific standard operating procedure describing additional steps used by the laboratory to confirm/adjudicate results. The status of controls should be reported for cases with 0% to 10% staining. Similar principles apply to PgR testing, which is used primarily for prognostic purposes in the setting of an ER-positive cancer. Testing of ductal carcinoma in situ (DCIS) for ER is recommended to determine potential benefit of endocrine therapies to reduce risk of future breast cancer, while testing DCIS for PgR is considered optional. Additional information can be found at www.asco.org/breast-cancer-guidelines.
To develop guideline recommendations concerning optimal neoadjuvant therapy for breast cancer.
ASCO convened an Expert Panel to conduct a systematic review of the literature on neoadjuvant therapy ...for breast cancer and provide recommended care options.
A total of 41 articles met eligibility criteria and form the evidentiary basis for the guideline recommendations.
Patients undergoing neoadjuvant therapy should be managed by a multidisciplinary care team. Appropriate candidates for neoadjuvant therapy include patients with inflammatory breast cancer and those in whom residual disease may prompt a change in therapy. Neoadjuvant therapy can also be used to reduce the extent of local therapy or reduce delays in initiating therapy. Although tumor histology, grade, stage, and estrogen, progesterone, and human epidermal growth factor receptor 2 (HER2) expression should routinely be used to guide clinical decisions, there is insufficient evidence to support the use of other markers or genomic profiles. Patients with triple-negative breast cancer (TNBC) who have clinically node-positive and/or at least T1c disease should be offered an anthracycline- and taxane-containing regimen; those with cT1a or cT1bN0 TNBC should not routinely be offered neoadjuvant therapy. Carboplatin may be offered to patients with TNBC to increase pathologic complete response. There is currently insufficient evidence to support adding immune checkpoint inhibitors to standard chemotherapy. In patients with hormone receptor (HR)-positive (HR-positive), HER2-negative tumors, neoadjuvant chemotherapy can be used when a treatment decision can be made without surgical information. Among postmenopausal patients with HR-positive, HER2-negative disease, hormone therapy can be used to downstage disease. Patients with node-positive or high-risk node-negative, HER2-positive disease should be offered neoadjuvant therapy in combination with anti-HER2-positive therapy. Patients with T1aN0 and T1bN0, HER2-positive disease should not be routinely offered neoadjuvant therapy.Additional information is available at www.asco.org/breast-cancer-guidelines.
To update key recommendations of the American Society of Clinical Oncology/College of American Pathologists estrogen receptor (ER) and progesterone receptor (PgR) testing in breast cancer guideline.
...A multidisciplinary international Expert Panel was convened to update the clinical practice guideline recommendations informed by a systematic review of the medical literature.
The Expert Panel continues to recommend ER testing of invasive breast cancers by validated immunohistochemistry as the standard for predicting which patients may benefit from endocrine therapy, and no other assays are recommended for this purpose. Breast cancer samples with 1% to 100% of tumor nuclei positive should be interpreted as ER positive. However, the Expert Panel acknowledges that there are limited data on endocrine therapy benefit for cancers with 1% to 10% of cells staining ER positive. Samples with these results should be reported using a new reporting category, ER Low Positive, with a recommended comment. A sample is considered ER negative if < 1% or 0% of tumor cell nuclei are immunoreactive. Additional strategies recommended to promote optimal performance, interpretation, and reporting of cases with an initial low to no ER staining result include establishing a laboratory-specific standard operating procedure describing additional steps used by the laboratory to confirm/adjudicate results. The status of controls should be reported for cases with 0% to 10% staining. Similar principles apply to PgR testing, which is used primarily for prognostic purposes in the setting of an ER-positive cancer. Testing of ductal carcinoma in situ (DCIS) for ER is recommended to determine potential benefit of endocrine therapies to reduce risk of future breast cancer, while testing DCIS for PgR is considered optional. Additional information can be found at www.asco.org/breast-cancer-guidelines .
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DOBA, IZUM, KILJ, NUK, OILJ, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK, VSZLJ
In early breast cancer, we integrate risk stratification and trial design, together with subtype, to focus on clinical questions in specific patient populations. In the past, trials enrolled an ...“all-comers,” broadly-defined population. More recently, trials enroll low-to intermediate-risk populations for whom testing strategies to de-escalate therapy are appropriate, or intermediate-to high-risk populations for whom testing additional and novel therapeutic strategies are needed. For example, in patients who have triple-negative breast cancer, the presence of residual disease after neoadjuvant therapy has become an approach to risk stratification for defining a trial population testing approaches to adjuvant therapy. In patients with hormone receptor positive, HER2-negative breast cancer, trials testing the addition of adjuvant CDK4/6 inhibitors to standard endocrine therapy have enrolled intermediate-to high-risk populations using various definitions and with heterogeneous results. Results of the recent generation of clinical trials testing systemic therapy for early breast cancer provide an opportunity to learn and improve future trial designs and accelerate progress to innovation for patients.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Summary Background For patients with breast cancer and metastases in the sentinel nodes, axillary dissection has been standard treatment. However, for patients with limited sentinel-node involvement, ...axillary dissection might be overtreatment. We designed IBCSG trial 23–01 to determine whether no axillary dissection was non-inferior to axillary dissection in patients with one or more micrometastatic (≤2 mm) sentinel nodes and tumour of maximum 5 cm. Methods In this multicentre, randomised, non-inferiority, phase 3 trial, patients were eligible if they had clinically non-palpable axillary lymph node(s) and a primary tumour of 5 cm or less and who, after sentinel-node biopsy, had one or more micrometastatic (≤2 mm) sentinel lymph nodes with no extracapsular extension. Patients were randomly assigned (in a 1:1 ratio) to either undergo axillary dissection or not to undergo axillary dissection. Randomisation was stratified by centre and menopausal status. Treatment assignment was not masked. The primary endpoint was disease-free survival. Non-inferiority was defined as a hazard ratio (HR) of less than 1·25 for no axillary dissection versus axillary dissection. The analysis was by intention to treat. Per protocol, disease and survival information continues to be collected yearly. This trial is registered with ClinicalTrials.gov , NCT00072293. Findings Between April 1, 2001, and Feb 28, 2010, 465 patients were randomly assigned to axillary dissection and 469 to no axillary dissection. After the exclusion of three patients, 464 patients were in the axillary dissection group and 467 patients were in the no axillary dissection group. After a median follow-up of 5·0 (IQR 3·6–7·3) years, we recorded 69 disease-free survival events in the axillary dissection group and 55 events in the no axillary dissection group. Breast-cancer-related events were recorded in 48 patients in the axillary dissection group and 47 in the no axillary dissection group (ten local recurrences in the axillary dissection group and eight in the no axillary dissection group; three and nine contralateral breast cancers; one and five regional recurrences; and 34 and 25 distant relapses). Other non-breast cancer events were recorded in 21 patients in the axillary dissection group and eight in the no axillary dissection group (20 and six second non-breast malignancies; and one and two deaths not due to a cancer event). 5-year disease-free survival was 87·8% (95% CI 84·4–91·2) in the group without axillary dissection and 84·4% (80·7–88·1) in the group with axillary dissection (log-rank p=0·16; HR for no axillary dissection vs axillary dissection was 0·78, 95% CI 0·55–1·11, non-inferiority p=0·0042). Patients with reported long-term surgical events (grade 3–4) included one sensory neuropathy (grade 3), three lymphoedema (two grade 3 and one grade 4), and three motor neuropathy (grade 3), all in the group that underwent axillary dissection, and one grade 3 motor neuropathy in the group without axillary dissection. One serious adverse event was reported, a postoperative infection in the axilla in the group with axillary dissection. Interpretation Axillary dissection could be avoided in patients with early breast cancer and limited sentinel-node involvement, thus eliminating complications of axillary surgery with no adverse effect on survival. Funding None.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Summary Background The International Metastatic Renal-Cell Carcinoma Database Consortium model offers prognostic information for patients with metastatic renal-cell carcinoma. We tested the accuracy ...of the model in an external population and compared it with other prognostic models. Methods We included patients with metastatic renal-cell carcinoma who were treated with first-line VEGF-targeted treatment at 13 international cancer centres and who were registered in the Consortium's database but had not contributed to the initial development of the Consortium Database model. The primary endpoint was overall survival. We compared the Database Consortium model with the Cleveland Clinic Foundation (CCF) model, the International Kidney Cancer Working Group (IKCWG) model, the French model, and the Memorial Sloan-Kettering Cancer Center (MSKCC) model by concordance indices and other measures of model fit. Findings Overall, 1028 patients were included in this study, of whom 849 had complete data to assess the Database Consortium model. Median overall survival was 18·8 months (95% 17·6–21·4). The predefined Database Consortium risk factors (anaemia, thrombocytosis, neutrophilia, hypercalcaemia, Karnofsky performance status <80%, and <1 year from diagnosis to treatment) were independent predictors of poor overall survival in the external validation set (hazard ratios ranged between 1·27 and 2·08, concordance index 0·71, 95% CI 0·68–0·73). When patients were segregated into three risk categories, median overall survival was 43·2 months (95% CI 31·4–50·1) in the favourable risk group (no risk factors; 157 patients), 22·5 months (18·7–25·1) in the intermediate risk group (one to two risk factors; 440 patients), and 7·8 months (6·5–9·7) in the poor risk group (three or more risk factors; 252 patients; p<0·0001; concordance index 0·664, 95% CI 0·639–0·689). 672 patients had complete data to test all five models. The concordance index of the CCF model was 0·662 (95% CI 0·636–0·687), of the French model 0·640 (0·614–0·665), of the IKCWG model 0·668 (0·645–0·692), and of the MSKCC model 0·657 (0·632–0·682). The reported versus predicted number of deaths at 2 years was most similar in the Database Consortium model compared with the other models. Interpretation The Database Consortium model is now externally validated and can be applied to stratify patients by risk in clinical trials and to counsel patients about prognosis. Funding None.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Purpose Estimating risk of late distant recurrence (DR) is an important goal for managing women with hormone receptor-positive breast cancer after 5 years of endocrine treatment without recurrence. ...We developed and validated a simple clinicopathologic tool (Clinical Treatment Score post-5 years CTS5) to estimate residual risk of DR after 5 years of endocrine treatment. Patients and Methods The ATAC (Arimidex, Tamoxifen, Alone or in Combination) data set (N = 4,735) was used to create a prognostic score for post-5-year risk of DR. Validity of CTS5 (ATAC) was tested in the BIG 1-98 data set (N = 6,711). Time to late DR, 5 years after finishing scheduled endocrine therapy, was the primary end point. Cox regression models estimated the prognostic performance of CTS5 (ATAC). Results CTS5 (ATAC) was significantly prognostic for late DR in the ATAC cohort (hazard ratio, 2.47; 95% CI, 2.24 to 2.73; P < .001) and BIG 1-98 validation cohort (hazard ratio, 2.07; 95% CI, 1.88 to 2.28; P < .001). CTS5 (ATAC) risk stratification defined in the training cohort as low (< 5% DR risk, years 5 to 10), intermediate (5% to 10%), or high (> 10%) identified 43% of the validation cohort as low risk, with an observed DR rate of 3.6% (95% CI, 2.7% to 4.9%) during years 5 to 10. From years 5 to 10, 63% of node-negative patients were low risk, with a DR rate of 3.9% (95% CI, 2.9% to 5.3%), and 24% with one to three positive nodes were low risk, with a DR rate of 1.5% (95% CI, 0.5% to 3.8%). A final CTS5 for future use was derived from pooled data from ATAC and BIG 1-98. Conclusion CTS5 is a simple tool based on information that is readily available to all clinicians. CTS5 was validated as highly prognostic for late DR in the independent BIG 1-98 study. The final CTS5 algorithm identified 42% of women with < 1% per-year risk of DR who could be advised of the limited potential value of extended endocrine therapy.
HER2-positive breast cancers usually contain large amounts of T-cell infiltrate. We hypothesised that trastuzumab resistance in HER2-positive breast cancer could be mediated by immune mechanisms. We ...assessed the safety and anti-tumour activity of pembrolizumab, a programmed cell death protein 1 (PD-1) inhibitor, added to trastuzumab in trastuzumab-resistant, advanced HER2-positive breast cancer.
We did this single-arm, multicentre, phase 1b–2 trial in 11 centres based in five countries. Eligible participants were women aged 18 years or older, who had advanced, histologically confirmed, HER2-positive breast cancer; documented progression during previous trastuzumab-based therapy; an Eastern Cooperative Oncology Group performance status of 0 or 1; and a formalin-fixed, paraffin-embedded metastatic tumour biopsy for central assessment of programmed cell death 1 ligand 1 (PD-L1) status. In phase 1b, we enrolled patients with PD-L1-positive tumours in a 3 + 3 dose-escalation of intravenous pembrolizumab (2 mg/kg and 10 mg/kg, every 3 weeks) plus 6 mg/kg of intravenous trastuzumab. The primary endpoint of the phase 1b study was the incidence of dose-limiting toxicity and recommended phase 2 dose; however, a protocol amendment on Aug 28, 2015, stipulated a flat dose of pembrolizumab of 200 mg every 3 weeks in all Merck-sponsored trials. In phase 2, patients with PD-L1-positive and PD-L1-negative tumours were enrolled in parallel cohorts and received the flat dose of pembrolizumab plus standard trastuzumab. The primary endpoint of the phase 2 study was the proportion of PD-L1-positive patients achieving an objective response. This trial is registered in ClinicalTrials.gov, number NCT02129556, and with EudraCT, number 2013-004770-10, and is closed.
Between Feb 2, 2015, and April 5, 2017, six patients were enrolled in phase 1b (n=3 received 2 mg/kg pembrolizumab, n=3 received 10 mg/kg pembrolizumab) and 52 patients in phase 2 (n=40 had PD-L1-positive tumours, n=12 had PD-L1-negative tumours). The data cutoff for this analysis was Aug 7, 2017. During phase 1b, there were no dose-limiting toxicities in the dose cohorts tested. Median follow-up for the phase 2 cohort was 13·6 months (IQR 11·6–18·4) for patients with PD-L1-positive tumours, and 12·2 months (7·9–12·2) for patients with PD-L1-negative tumours. Six (15%, 90% CI 7–29) of 40 PD-L1-positive patients achieved an objective response. There were no objective responders among the PD-L1-negative patients. The most common treatment-related adverse event of any grade was fatigue (12 21% of 58 patients). Grade 3–5 adverse events occurred in 29 (50%) of patients, treatment-related grade 3–5 adverse events occurred in 17 (29%), and serious adverse events occurred in 29 (50%) patients. The most commonly occurring serious adverse events were dyspnoea (n=3 5%), pneumonitis (n=3 5%), pericardial effusion (n=2 3%), and upper respiratory infection (n=2 3%). There was one treatment-related death due to Lambert-Eaton syndrome in a PD-L1-negative patient during phase 2.
Pembrolizumab plus trastuzumab was safe and showed activity and durable clinical benefit in patients with PD-L1-positive, trastuzumab-resistant, advanced, HER2-positive breast cancer. Further studies in this breast cancer subtype should focus on a PD-L1-positive population and be done in less heavily pretreated patients.
Merck, International Breast Cancer Study Group.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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