{"id":{"repo_id":"toronto-retro","oai_identifier":"oai:utoronto.scholaris.ca:1807/129808"},"canonical_url":"https://search.dev.ndltd.org/etd/toronto-retro/oai:utoronto.scholaris.ca:1807/129808","repository":{"repo_id":"toronto-retro","name":"University of Toronto","base_url":"https://utoronto.scholaris.ca/server/oai/request"},"display":{"title":"Practice Patterns and Health Outcomes of Adjuvant Oxaliplatin Chemotherapy for Colorectal Cancer","abstract":"INTRODUCTION: Oxaliplatin-containing adjuvant chemotherapy improves survival for stage III colon cancer. Yet it is not without harms, most commonly dose-dependent peripheral neuropathy. The 2018 International Duration Evaluation of Adjuvant Chemotherapy (IDEA) trial sought to determine the optimal duration of adjuvant therapy by evaluating the non-inferiority (NI) of 3 versus 6 months of treatment. The 3-year disease-free survival probability was 74.6% in the 3-month group versus 75.5% in the 6-month group (HR 1.07, 95% CI 1.00-1.15; pNI = 0.11). There remain open questions regarding how these findings changed practice, whether these outcomes are obtained in the general population, and – given oxaliplatin-induced neuropathy – the relationship between treatment duration and post-treatment falls. METHODS: We leveraged linked administrative and population-based datasets held at ICES to conduct three retrospective cohort studies of patients with stage III colon cancer in Ontario, Canada. First, we employed interrupted time series regression and mixed models to evaluate the association between IDEA’s publication and prescribed treatment durations. Second, we utilized overlap propensity score-weighted survival models to determine the relationship between treatment duration and mortality. Third, we again used weighted survival models to examine the association between treatment duration and fall-related injury. RESULTS: IDEA’s publication was associated with a 16.4% (95% CI 12.5-20.3%) absolute increase in patients treated with ≤50% of a 6-month course of therapy. Between-prescriber variation strongly influenced treatment duration in the post-IDEA period (median odds ratio 2.10 [95% CI 1.73-3.18] for short-duration treatment). Treatment with 50% of a 6-month course of therapy was associated with a HR of 1.13 (95% CI 0.88-1.47) for overall mortality versus >85% of a 6-month course of therapy. Meanwhile, treatment with >85% of a 6-month course of therapy conferred a HR of 0.84 (95% CI 0.62-1.13) for fall-related injury. CONCLUSION: Although IDEA could not conclude non-inferiority of 3 to 6 months of adjuvant therapy, the trial rapidly shifted clinical practice while introducing greater provider-level practice variation. While intuitive concerns about the relationship between oxaliplatin and fall-related injury are not borne out in the data, evidence from routine practice solidifies that treatment duration is a preference-sensitive decision involving a tradeoff between survival and toxicity.","abstract_html":"INTRODUCTION: Oxaliplatin-containing adjuvant chemotherapy improves survival for stage III colon cancer. Yet it is not without harms, most commonly dose-dependent peripheral neuropathy. The 2018 International Duration Evaluation of Adjuvant Chemotherapy (IDEA) trial sought to determine the optimal duration of adjuvant therapy by evaluating the non-inferiority (NI) of 3 versus 6 months of treatment. The 3-year disease-free survival probability was 74.6% in the 3-month group versus 75.5% in the 6-month group (HR 1.07, 95% CI 1.00-1.15; pNI = 0.11). There remain open questions regarding how these findings changed practice, whether these outcomes are obtained in the general population, and – given oxaliplatin-induced neuropathy – the relationship between treatment duration and post-treatment falls. METHODS: We leveraged linked administrative and population-based datasets held at ICES to conduct three retrospective cohort studies of patients with stage III colon cancer in Ontario, Canada. First, we employed interrupted time series regression and mixed models to evaluate the association between IDEA’s publication and prescribed treatment durations. Second, we utilized overlap propensity score-weighted survival models to determine the relationship between treatment duration and mortality. Third, we again used weighted survival models to examine the association between treatment duration and fall-related injury. RESULTS: IDEA’s publication was associated with a 16.4% (95% CI 12.5-20.3%) absolute increase in patients treated with ≤50% of a 6-month course of therapy. Between-prescriber variation strongly influenced treatment duration in the post-IDEA period (median odds ratio 2.10 [95% CI 1.73-3.18] for short-duration treatment). Treatment with 50% of a 6-month course of therapy was associated with a HR of 1.13 (95% CI 0.88-1.47) for overall mortality versus >85% of a 6-month course of therapy. Meanwhile, treatment with >85% of a 6-month course of therapy conferred a HR of 0.84 (95% CI 0.62-1.13) for fall-related injury. CONCLUSION: Although IDEA could not conclude non-inferiority of 3 to 6 months of adjuvant therapy, the trial rapidly shifted clinical practice while introducing greater provider-level practice variation. While intuitive concerns about the relationship between oxaliplatin and fall-related injury are not borne out in the data, evidence from routine practice solidifies that treatment duration is a preference-sensitive decision involving a tradeoff between survival and toxicity.","abstract_has_math":false,"creators":["Sue-Chue-Lam, Colin James"],"institution":null,"degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":"Dalla Lana School of Public Health","school":null,"contributors":[],"advisors":["Baxter, Nancy N"],"committee_chairs":[],"committee_members":[],"year":2023,"date_issued":"2023-11","date_published":"2023-11","updated_at":"2026-07-27T21:27:56Z","subjects":["chemotherapy","colorectal cancer","neuropathy","non-inferiority","oxaliplatin","practice variation"],"languages":[],"rights":["Attribution-NonCommercial-ShareAlike 4.0 International"],"rights_urls":["http://creativecommons.org/licenses/by-nc-sa/4.0/"],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/1807/129808","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Baxter, Nancy N"]},{"key":"dc:contributor.department","label":"Department","values":["Dalla Lana School of Public Health"]},{"key":"dc:creator","label":"Author","values":["Sue-Chue-Lam, Colin James"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2023-11"]},{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2023-11-13T16:11:04Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2023-11-13T16:11:04Z"]},{"key":"dc:date.issued","label":"Date","values":["2023-11"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["chemotherapy","colorectal cancer","neuropathy","non-inferiority","oxaliplatin","practice variation"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:rights","label":"Dc Rights","values":["Attribution-NonCommercial-ShareAlike 4.0 International"]},{"key":"dc:rights.uri","label":"Rights URI","values":["http://creativecommons.org/licenses/by-nc-sa/4.0/"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/1807/129808"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["INTRODUCTION: Oxaliplatin-containing adjuvant chemotherapy improves survival for stage III colon cancer. Yet it is not without harms, most commonly dose-dependent peripheral neuropathy. The 2018 International Duration Evaluation of Adjuvant Chemotherapy (IDEA) trial sought to determine the optimal duration of adjuvant therapy by evaluating the non-inferiority (NI) of 3 versus 6 months of treatment. The 3-year disease-free survival probability was 74.6% in the 3-month group versus 75.5% in the 6-month group (HR 1.07, 95% CI 1.00-1.15; pNI = 0.11). There remain open questions regarding how these findings changed practice, whether these outcomes are obtained in the general population, and – given oxaliplatin-induced neuropathy – the relationship between treatment duration and post-treatment falls. METHODS: We leveraged linked administrative and population-based datasets held at ICES to conduct three retrospective cohort studies of patients with stage III colon cancer in Ontario, Canada. First, we employed interrupted time series regression and mixed models to evaluate the association between IDEA’s publication and prescribed treatment durations. Second, we utilized overlap propensity score-weighted survival models to determine the relationship between treatment duration and mortality. Third, we again used weighted survival models to examine the association between treatment duration and fall-related injury. RESULTS: IDEA’s publication was associated with a 16.4% (95% CI 12.5-20.3%) absolute increase in patients treated with ≤50% of a 6-month course of therapy. Between-prescriber variation strongly influenced treatment duration in the post-IDEA period (median odds ratio 2.10 [95% CI 1.73-3.18] for short-duration treatment). Treatment with 50% of a 6-month course of therapy was associated with a HR of 1.13 (95% CI 0.88-1.47) for overall mortality versus >85% of a 6-month course of therapy. Meanwhile, treatment with >85% of a 6-month course of therapy conferred a HR of 0.84 (95% CI 0.62-1.13) for fall-related injury. CONCLUSION: Although IDEA could not conclude non-inferiority of 3 to 6 months of adjuvant therapy, the trial rapidly shifted clinical practice while introducing greater provider-level practice variation. While intuitive concerns about the relationship between oxaliplatin and fall-related injury are not borne out in the data, evidence from routine practice solidifies that treatment duration is a preference-sensitive decision involving a tradeoff between survival and toxicity."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["Ph.D."]},{"key":"dc:title","label":"Title","values":["Practice Patterns and Health Outcomes of Adjuvant Oxaliplatin Chemotherapy for Colorectal Cancer"]}]}],"canonical_facts":{"dc:contributor.advisor":["Baxter, Nancy N"],"dc:contributor.department":["Dalla Lana School of Public Health"],"dc:creator":["Sue-Chue-Lam, Colin James"],"dc:date":["2023-11"],"dc:date.accessioned":["2023-11-13T16:11:04Z"],"dc:date.available":["2023-11-13T16:11:04Z"],"dc:date.issued":["2023-11"],"dc:description.abstract":["INTRODUCTION: Oxaliplatin-containing adjuvant chemotherapy improves survival for stage III colon cancer. Yet it is not without harms, most commonly dose-dependent peripheral neuropathy. The 2018 International Duration Evaluation of Adjuvant Chemotherapy (IDEA) trial sought to determine the optimal duration of adjuvant therapy by evaluating the non-inferiority (NI) of 3 versus 6 months of treatment. The 3-year disease-free survival probability was 74.6% in the 3-month group versus 75.5% in the 6-month group (HR 1.07, 95% CI 1.00-1.15; pNI = 0.11). There remain open questions regarding how these findings changed practice, whether these outcomes are obtained in the general population, and – given oxaliplatin-induced neuropathy – the relationship between treatment duration and post-treatment falls. METHODS: We leveraged linked administrative and population-based datasets held at ICES to conduct three retrospective cohort studies of patients with stage III colon cancer in Ontario, Canada. First, we employed interrupted time series regression and mixed models to evaluate the association between IDEA’s publication and prescribed treatment durations. Second, we utilized overlap propensity score-weighted survival models to determine the relationship between treatment duration and mortality. Third, we again used weighted survival models to examine the association between treatment duration and fall-related injury. RESULTS: IDEA’s publication was associated with a 16.4% (95% CI 12.5-20.3%) absolute increase in patients treated with ≤50% of a 6-month course of therapy. Between-prescriber variation strongly influenced treatment duration in the post-IDEA period (median odds ratio 2.10 [95% CI 1.73-3.18] for short-duration treatment). Treatment with 50% of a 6-month course of therapy was associated with a HR of 1.13 (95% CI 0.88-1.47) for overall mortality versus >85% of a 6-month course of therapy. Meanwhile, treatment with >85% of a 6-month course of therapy conferred a HR of 0.84 (95% CI 0.62-1.13) for fall-related injury. CONCLUSION: Although IDEA could not conclude non-inferiority of 3 to 6 months of adjuvant therapy, the trial rapidly shifted clinical practice while introducing greater provider-level practice variation. While intuitive concerns about the relationship between oxaliplatin and fall-related injury are not borne out in the data, evidence from routine practice solidifies that treatment duration is a preference-sensitive decision involving a tradeoff between survival and toxicity."],"dc:description.degree":["Ph.D."],"dc:identifier.uri":["http://hdl.handle.net/1807/129808"],"dc:rights":["Attribution-NonCommercial-ShareAlike 4.0 International"],"dc:rights.uri":["http://creativecommons.org/licenses/by-nc-sa/4.0/"],"dc:subject":["chemotherapy","colorectal cancer","neuropathy","non-inferiority","oxaliplatin","practice variation"],"dc:title":["Practice Patterns and Health Outcomes of Adjuvant Oxaliplatin Chemotherapy for Colorectal Cancer"],"dc:type":["Thesis"]},"updated_at":"2026-07-27T21:27:56Z"}