Use of Surgical Procedures and Adjuvant Therapy in Rectal Cancer
Use of Surgical Procedures and Adjuvant Therapy in Rectal Cancer
Abstract & Commentary
Synopsis: This study examines type of surgical therapy and application of NIH recommendations for rectal cancer patients on a population level, using patient-level data from electronic charts in a regional tumor registry. The use of sphincter-sparing vs. sphincter-ablating surgery and compliance with National Institutes of Health Consensus Conference recommendations was evaluated for differences among hospital, surgeon, and patient groups, stratified by tumor stage and location. Factors significantly associated with sphincter-sparing surgery included female gender, middle-rectum tumor location, and major teaching hospital setting. Factors significantly associated with recommended adjuvant therapy included younger patient age, middle or lower rectum tumor location, stage III disease, and teaching hospital setting.
Source: Schroen AT, Cress RD. Ann Surg. 2001;234:641-651.
Since approximately 1990, the dominant surgical therapy for rectal cancer has increasingly shifted from abdominoperineal resection (APR), with permanent colostomy and sphincter ablation, to low anterior resection (LAR), with bowel continuity and sphincter preservation. Also in 1990, the National Institutes of Health (NIH) released consensus conference recommendations for adjuvant treatment for stage II and III rectal cancer.1 For rectal cancer patients, type of surgical resection and adjuvant (or neoadjuvant) therapy are closely linked by local and regional control issues. Sphincter-sparing surgery can potentially enhance patient quality of life but must provide adequate local control, which in turn is promoted by appropriate adjuvant therapy. Furthermore, appropriate adjuvant therapy (combined radiation and chemotherapy for stage II and III disease) has been shown to improve both local recurrence rates and overall survival for rectal cancer patients.
Population-based studies have examined the applications of both surgical and adjuvant therapies for rectal cancer but have been limited by lack of more specific patient- and disease-related data. Single institution studies have examined use and outcomes of these therapies but have been unable to address their wider application. In the current study, Schroen and Cress investigated type of surgical therapy performed and application of NIH recommendations on a population level by abstracting patient-level data from electronic charts within a regional tumor registry.
Between 1994 and 1996, 637 patients with incident invasive rectal adenocarcinoma were reported to the electronic Cancer Surveillance Program, Region 3, of the California Cancer Registry, with an estimated 98% complete ascertainment level in 1996. Patient level data included age, gender, race, and American Joint Committee on Cancer stage at diagnosis (with approximately 90% accuracy per registrar staging). Type of surgical procedure, receipt of adjuvant radiation therapy, and provision of radiation therapy and chemotherapy were recorded. Tumor location, which has direct bearing on feasibility of sphincter-sparing operation, was derived from text files abstracted from patient charts. With the anal verge as reference point, lower rectum was deemed 0-5 cm, middle was 6-10 cm, and upper was 10-15 cm. Surgeon type designation (general vs colorectal) was based on self-reported specialty from American Medical Association physician information. Hospital characteristics included bed number, teaching status, location in Region 3, and presence of an American College of Surgeons-approved cancer program.
Text fields were not required by the registry until after 1994 and, therefore, were available for a total of 497 patients. Among these, tumor location could be identified in 407 patients (82%). Among the 440 patients for whom operating surgeon could be identified, 75% underwent care by a general surgeon. Although stage of tumor was evenly distributed among general and colorectal surgeons, colorectal surgeons treated significantly younger patients, more patients seen at teaching hospitals, and more patients with middle and lower rectal tumors.
For all patients, even those with stage I disease, LAR and APR were the most common procedures performed. Rate of APR use was highly dependent upon tumor location, increasing from 0% to 22% to 55% for tumors in the upper, middle, and lower rectum, respectively. In the middle and lower rectum, LAR use was 71% and 19%, respectively (P < 0.001). Middle rectal tumors (n = 108) are arguably those with the greatest technical potential for sphincter sparing. Colorectal surgeons performed fewer APRs for this group than general surgeons (15% vs 29%, respectively) and more LARs (74% vs 66%, respectively), but these rates did not reach statistical significance. Similarly, for lower rectal tumors, there was no significant difference in procedure performance between the specialties. The only hospital characteristic associated with type of resection was teaching designation. LARs were performed much more frequently in major teaching hospitals (odds ratio [OR] = 5.19; confidence interval [CI], 1.56-17.26). This finding disappeared for hospitals associated with a major academic medical center.
Receipt of any radiation therapy or chemotherapy was greater than 50% among patients with stage II disease and greater than 60% among those with stage III disease (P < 0.01). Among patients with stage II and stage III disease, patient characteristic with the greatest effect on receipt of adjuvant therapy was patient age. Patients younger than 60 years were 9 times more likely to receive some adjuvant therapy compared to those older than 75 years (CI, 4.26-21.29). Patients 60-75 years were about 4 times more likely to receive adjuvant therapy than those older than 75 years. Patients with middle and lower rectal tumors were significantly more likely to receive adjuvant therapy than those with upper rectal tumors. Patients in teaching hospitals were also more likely to undergo adjuvant therapy, but this rate was only significant for those in minor teaching hospitals (hospitals with fewer than 4 residency types) and again disappeared for hospitals associated with a major academic medical center.
In summary, this study found that patients with similarly staged and located rectal tumors underwent different treatment regimens, which could not be wholly explained by clinical data. Female gender, tumor located in the middle rectum, and treatment in a major teaching hospital (but not a major academic medical center) were significantly associated with performance of a sphincter-sparing procedure. Younger age, stage III tumor, tumor located in the middle or lower rectum, and treatment in a minor teaching hospital were significantly associated with compliance with NIH adjuvant therapy recommendations for stage II and III disease.
Comment by Arden Morris, MD
In using state tumor registry data, this study sought to overcome the complementary limitations inherent in large population-based studies and smaller single institution studies, with partial success. Schroen and Cress were able to obtain relevant clinical data, which assisted in approaching the evaluation of appropriateness of surgical procedure provided. The study found a surprisingly high use of APR overall (31%), but were stymied in defining predictors by a substantially incomplete data set. For example, text to determine tumor location was only available for 78% of patients (497/637) and could be determined in 64% of patients overall (407/637). Moreover, the effect of surgical specialty did not reach statistical significance, perhaps because these data were missing for 197 patients. Still, Schroen and Cress were able to show that middle rectal tumors are (appropriately) increasingly resected by sphincter-sparing means and that major teaching hospitals are more frequently performing this procedure, a finding supported within the medical literature. The decreased likelihood of sphincter sparing at hospitals associated with major academic medical centers is difficult to explain and may well be a power issue, since this is a scarce entity in central California (Region 3).
The study also undertook to examine provision of radiation and chemotherapy, per 1990 NIH Consensus Conference recommendations. Again database limitations intervened and receipt of radiation or chemotherapy could only be recorded as a dichotomous variable, thus actual regimens and completion of therapy were unknown. Furthermore, data regarding the receipt of outpatient chemotherapy were not available, which may have biased results considerably. Nevertheless, for patients with stage II and III disease, the reported "compliance with recommended therapy" contained some interesting results. Consistent with recent literature, increased age had a substantially negative effect on receipt of adjuvant therapy despite NIH recommendations, with patients older than age 75 years 9 times less likely than those younger than age 60 to receive combined adjuvant treatment. Even among patients younger than age 60, only 1 in 4 received recommended therapy. However, this study also reveals that use of adjuvant therapy has increased more than 20% for patients with stage II and III disease when compared with National Cancer Data Base reports from 1990.
Finally, this study did not include information about patient outcomes, preferring instead to focus on treatment provided. After now defining the therapies these patients actually underwent, a future look at associated recurrence and survival might be interesting, despite the power limitations described above.
Reference
1. NIH Consensus Conference. Adjuvant therapy for patients with colon and rectal cancer. JAMA. 1990; 264:1444-1450.
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