Early Colonoscopy Confers Survival Benefits on Colon Cancer Patients with Pre-Existing Iron Deficiency Anemia: A Nationwide Population-Based Study

<div><p>This study aimed to examine the prognostic significance of pre-existing iron deficiency anemia (IDA) and the benefits of early colonoscopy in patients with colon cancer, since these have not been clearly established to date. Using the Taiwanese National Health Insurance Research Database, we retrieved and retrospectively reviewed the records of patients aged ≥55 years who were diagnosed with colon cancer between 2000 and 2005. The patient cohort was divided into two groups: patients with (n = 1,260) or without (n = 15,912) an IDA diagnosis during ≤18 months preceding the date of colon cancer diagnosis. We found that diabetes (27.9% vs. 20.3%, p<0.0001), cardiovascular disease (61.6% vs. 54.7%, p<0.001), and chronic kidney disease (4.6% vs. 2.2%, p<0.0001) were more common among patients with IDA than among those without IDA. The median overall survival times for patients with IDA and those without IDA were 4.6 and 5.7 years, respectively (p = 0.002). Patients who underwent colonoscopy ≤30 days, 31–90, and ≥91 days after IDA diagnosis showed median overall survival times of 5.79, 4.43, and 4.04 years, respectively (p = 0.003). Delayed colonoscopy was an independent factor associated with poor overall survival (adjusted hazard ratio, 1.28; 95% confidence interval, 1.07–1.53; p = 0.01). In conclusion, colon cancer patients with IDA were more likely to experience comorbidities than were those without IDA. Pre-existing IDA was a poor prognostic factor in adult men and postmenopausal women who had colon cancer. Early colonoscopy could improve overall survival possibly by facilitating early diagnosis and treatment.</p></div

Comparison of Clinical Characteristics of Metastatic Colorectal Cancer Patients According to Front-line Treatment.

<p>SD: standard deviation; CCI: Charlson comorbidity index; CVD: cardiovascular disease; CKD: chronic kidney disease.</p><p>^aANOVA for continuous variables</p><p>^bChi-square test for categorical variables.</p><p>Comparison of Clinical Characteristics of Metastatic Colorectal Cancer Patients According to Front-line Treatment.</p

Survival comparison according to interval between diagnosis of iron deficiency anemia (IDA) and colon cancer.

<p>For colon cancer patients with pre-existing IDA, their overall survival times were compared according to the interval between IDA diagnosis and colon cancer confirmation (≤30 days, 31–90 days, and ≥91 days) and are presented with Kaplan–Meir survival curves. (A) For all patients together, (B) for those with stage I/II disease, and (C) for those with stage III/IV disease.</p

Patient selection and stratification.

<p>Patient selection and stratification.</p

Hazard Ratios For Death According to Interval Between IDA and Colon Cancer Diagnosis, Adjusted For Covariates^* Using A Cox Proportional Hazards Model.

<p>IDA: iron deficiency anemia; CI: confidence interval.</p>*<p>Age, gender, hypertension, diabetes mellitus, hyperlipidemia, cardiovascular disease, and chronic kidney disease.</p

Clinical Characteristics According to Interval Between IDA and Colon Cancer Diagnosis.

<p>IDA: iron deficiency anemia; SD: standard deviation; DM: diabetes mellitus; CVD: cardiovascular disease; CKD: chronic kidney disease.</p>a<p>indicates an ANOVA test;</p>b<p>indicates a chi-squared.</p

Overall survival (OS) comparison among colon cancer patients with and without iron deficiency anemia (IDA).

<p>Among adult male and postmenopausal female colon cancer patients, median OS times were 4.6 and 5.7 years for patients with per-existing IDA and those without per-existing IDA, respectively. Patients with pre-existing IDA had inferior OS compared to those without pre-existing IDA (<i>p</i> = 0.002).</p

Clinical Characteristics of Colon Cancer Patients With and Without Pre-existing IDA.

<p>IDA: iron deficiency anemia; SD: standard deviation; DM: diabetes mellitus; CVD: cardiovascular diseases; CKD: chronic kidney disease.</p>a<p>indicates an ANOVA test;</p>b<p>indicates a chi-square test.</p

Comparison of survival in metastatic colorectal cancer patients treated with irinotecan followed by oxaliplatin-based regimens or the reverse sequence.

<p>The median first time to next treatment (TTNT1) in arm A (irinotecan followed by oxaliplatin-based regimens) was 210 days (14−2048). It was 196 days (14−2004) in arm B (oxaliplatin followed by irinotecan-based regimens). TTNT1 was not significantly different between patients in arm A and arm B (p = 0.17). Moreover, the median second time to next treatment (TTNT2) in arm A and arm B was 155 days (14−1666) and 123 days (14−1460), respectively. TTNT2 was longer for patients in arm A than for those in arm B (p = 0.006). In terms of overall survival (OS), the median OS time for arm A and arm B was 487 days (87−2161) and 454 days (56−1918), respectively. OS was significantly longer for patients in arm A than for those in arm B (p = 0.02).</p

Subgroup analyses of overall survival for oxaliplatin followed by irinotecan-based regimens versus the reverse sequence.

<p>The overall hazard ratio (HR) for oxaliplatin followed by irinotecan-based regimens (arm A) versus the reverse sequence (arm B) was 1.06 (95% confidence interval [CI]: 0.95−1.19; p = 0.27). Age, gender, hypertension, diabetes, hyperlipidemia, cardiovascular disease, and chronic kidney disease were not independently associated with better overall survival in patients receiving either chemotherapy sequence.</p