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Dive into the research topics where Alan G. Thorson is active.

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Featured researches published by Alan G. Thorson.


Gastroenterology | 2008

Screening and surveillance for the early detection of colorectal cancer and adenomatous polyps, 2008: a joint guideline from the American Cancer Society, the US Multi-Society Task Force on Colorectal Cancer, and the American College of Radiology.

Bernard Levin; David A. Lieberman; Beth McFarland; Kimberly S. Andrews; Durado Brooks; John H. Bond; Chiranjeev Dash; Francis M. Giardiello; Seth N. Glick; David A. Johnson; C. Daniel Johnson; Theodore R. Levin; Perry J. Pickhardt; Douglas K. Rex; Robert A. Smith; Alan G. Thorson; Sidney J. Winawer

In the United States, colorectal cancer (CRC) is the third most common cancer diagnosed among men and women and the second leading cause of death from cancer. CRC largely can be prevented by the detection and removal of adenomatous polyps, and survival is significantly better when CRC is diagnosed while still localized. In 2006 to 2007, the American Cancer Society, the US Multi-Society Task Force on Colorectal Cancer, and the American College of Radiology came together to develop consensus guidelines for the detection of adenomatous polyps and CRC in asymptomatic average-risk adults. In this update of each organizations guidelines, screening tests are grouped into those that primarily detect cancer early and those that can detect cancer early and also can detect adenomatous polyps, thus providing a greater potential for prevention through polypectomy. When possible, clinicians should make patients aware of the full range of screening options, but at a minimum they should be prepared to offer patients a choice between a screening test that primarily is effective at early cancer detection and a screening test that is effective at both early cancer detection and cancer prevention through the detection and removal of polyps. It is the strong opinion of these 3 organizations that colon cancer prevention should be the primary goal of screening.


CA: A Cancer Journal for Clinicians | 2008

Screening and Surveillance for the Early Detection of Colorectal Cancer and Adenomatous Polyps, 2008: A Joint Guideline from the American Cancer Society, the US Multi‐Society Task Force on Colorectal Cancer, and the American College of Radiology*†

Bernard Levin; David A. Lieberman; Beth McFarland; Robert A. Smith; Durado Brooks; Kimberly S. Andrews; Chiranjeev Dash; Francis M. Giardiello; Seth N. Glick; Theodore R. Levin; Perry J. Pickhardt; Douglas K. Rex; Alan G. Thorson; Sidney J. Winawer

In the United States, colorectal cancer (CRC) is the third most common cancer diagnosed among men and women and the second leading cause of death from cancer. CRC largely can be prevented by the detection and removal of adenomatous polyps, and survival is significantly better when CRC is diagnosed while still localized. In 2006 to 2007, the American Cancer Society, the US Multi Society Task Force on Colorectal Cancer, and the American College of Radiology came together to develop consensus guidelines for the detection of adenomatous polyps and CRC in asymptomatic average‐risk adults. In this update of each organizations guidelines, screening tests are grouped into those that primarily detect cancer early and those that can detect cancer early and also can detect adenomatous polyps, thus providing a greater potential for prevention through polypectomy. When possible, clinicians should make patients aware of the full range of screening options, but at a minimum they should be prepared to offer patients a choice between a screening test that is effective at both early cancer detection and cancer prevention through the detection and removal of polyps and a screening test that primarily is effective at early cancer detection. It is the strong opinion of these 3 organizations that colon cancer prevention should be the primary goal of screening.


Diseases of The Colon & Rectum | 2000

Fecal incontinence quality of life scale

Todd H. Rockwood; James M. Church; James W. Fleshman; Robert L. Kane; Constantinos Mavrantonis; Alan G. Thorson; Steven D. Wexner; Donna Z. Bliss; Ann C. Lowry

PURPOSE: This goal of this research was to develop and evaluate the psychometrics of a health-related quality of life scale developed to address issues related specifically to fecal incontinence, the Fecal Incontinence Quality of Life Scale. METHODS: The Fecal Incontinence Quality of Life Scale is composed of a total of 29 items; these items form four scales: Lifestyle (10 items), Coping/Behavior (9 items), Depression/Self-Perception (7 items), and Embarrassment (3 items). RESULTS: Psychometric evaluation of these scales demonstrates that they are both reliable and valid. Each of the scales demonstrate stability over time (test/retest reliability) and have acceptable internal reliability (Cronbach alpha >0.70). Validity was assessed using discriminate and convergent techniques. Each of the four scales of the Fecal Incontinence Quality of Life Scale was capable of discriminating between patients with fecal incontinence and patients with other gastrointestinal problems. To evaluate convergent validity, the correlation of the scales in the Fecal Incontinence Quality of Life Scale with selected subscales in the SF-36 was analyzed. The scales in the Fecal Incontinence Quality of Life Scale demonstrated significant correlations with the subscales in the SF-36. CONCLUSIONS: The psychometric evaluation of the Fecal Incontinence Quality of Life Scale showed that this fecal incontinence-specific quality of life measure produces both reliable and valid measurement.


Diseases of The Colon & Rectum | 1999

Patient and surgeon ranking of the severity of symptoms associated with fecal incontinence: the fecal incontinence severity index.

Todd H. Rockwood; James M. Church; James W. Fleshman; Robert L. Kane; Constantinos Mavrantonis; Alan G. Thorson; Steven D. Wexner; R N Donna Bliss; Ann C. Lowry

PURPOSE: The purpose of this research was to develop and evaluate a severity rating score for fecal incontinence, the Fecal Incontinence Severity Index. METHODS: The Fecal Incontinence Severity Index is based on a type × frequency matrix. The matrix includes four types of leakage commonly found in the fecal incontinent population: gas, mucus, and liquid and solid stool and five frequencies: one to three times per month, once per week, twice per week, once per day, and twice per day. The Fecal Incontinence Severity Index was developed using both colon and rectal surgeons and patient input for the specification of the weighting scores. RESULTS: Surgeons and patients had very similar weightings for each of the type × frequency combinations; significant differences occurred for only 3 of the 20 different weights. The Fecal Incontinence Severity Index score of a group of patients with fecal incontinence (N = 118) demonstrated significant correlations with three of the four scales found in a fecal incontinence quality-of-life scale. CONCLUSIONS: Evaluation of the Fecal Incontinence Severity Index indicates that the index is a tool that can be used to assess severity of fecal incontinence. Overall, patient and surgeon ratings of severity are similar, with minor differences associated with the accidental loss of solid stool.


Diseases of The Colon & Rectum | 1993

Laparoscopic colectomy: A critical appraisal

P. M. Falk; Robert W. Beart; Steven D. Wexner; Alan G. Thorson; David G. Jagelman; Ian C. Lavery; Olaf B. Johansen; Robert J. Fitzgibbons

A multicenter retrospective study was undertaken to assess the efficacy and safety of laparoscopy in colon and rectal surgery. To minimize potential bias in interpretation of the results, all data were registered with an independent observer, who did not participate in any of the surgical procedures. Sixty-six patients underwent a laparoscopic procedure. Operations performed included sigmoid colectomy (19), right hemicolectomy (15), low anterior resection (6), colectomy with ileal pouch-anal anastomosis (IPAA) (5), and abdominoperineal resection (APR) (3). The conversion rate from laparoscopic colectomy to celiotomy was 41 percent. Major morbidity and mortality were 24 percent and 0 percent, respectively. Length of stay, hospital costs, and lymph node harvest were compared between the sigmoid resection and right hemicolectomy subgroups. Data from traditional sigmoid colectomies and right hemicolectomies were obtained from the same institutions for comparison. Mean postoperative stay for laparoscopically completed sigmoid and right colectomies was significantly less than that for either the converted or the traditional groups (P<0.02). Total hospital cost for traditional right hemicolectomy was significantly less than that for the converted group (P< 0.05) but not the laparoscopic group. Laparoscopic sigmoid resection showed no significant total hospital cost difference among traditional, converted, and laparoscopic groups. Lymph node harvest in resections for carcinoma was comparable in all groups. These preliminary data suggest that laparoscopic colon and rectal surgery can be accomplished with acceptable morbidity and mortality when performed by trained surgeons. Length of stay is shorter, but there is no proven total hospital cost benefit. Appropriate registries will be necessary to adequately assess long-term outcome.


Cancer | 1998

Colorectal carcinoma survival among hereditary nonpolyposis colorectal carcinoma family members

Patrice Watson; Kevin M. Lin; Miguel A. Rodriguez-Bigas; Tom Smyrk; Stephen J. Lemon; Maniamparampil Shashidharan; Barbara Franklin; Beth Karr; Alan G. Thorson; Henry T. Lynch

Patients with hereditary nonpolyposis colorectal carcinoma (HNPCC) reportedly have better prognoses than sporadic colorectal carcinoma (CRC) patients, but it has been unclear whether this could be due to differences in stage at diagnosis. The current study compared stage and survival in a retrospective cohort of HNPCC family members who developed CRC with the same factors in an unselected hospital series of patients with sporadic CRC.


Diseases of The Colon & Rectum | 1993

Cumulative incidence of metachronous colorectal cancer

Rebecca L. Cali; Richard M. Pitsch; Alan G. Thorson; Patrice Watson; Paul Tapia; Garnet J. Blatchford; Mark A. Christensen

The incidence of metachronous colorectal cancer has most often been reported as a crude rate: second cancers/index cancers. The reported incidence varies between 0.5 percent and 3.6 percent. However, these calculations do not take into account factors such as length of survival and length of follow-up. The cumulative incidence more accurately reflects the risk for developing a metachronous cancer and was determined in a retrospective analysis of 5,476 patients who were diagnosed with colon or rectal cancer between 1965 and 1985. The cumulative probability was calculated by determining the number of patients developing a metachronous colon cancervs.the number remaining at risk at that point in time. The calculated annual incidence for metachronous tumors was 0.35 percent per year. The cumulative incidence at 18 years was 6.3 percent. Analysis also demonstrated that metachronous cancers were diagnosed at earlier stages than were index cancers (P=0.03). Subgroup analysis was performed on patients diagnosed with metachronous cancer before and after 1980. There was a difference in the incidence of metachronous cancers between these two groups (P=0.04).


Diseases of The Colon & Rectum | 1988

Repair of simple rectovaginal fistulas. Influence of previous repairs.

Ann C. Lowry; Alan G. Thorson; David A. Rothenberger; Stanley M. Goldberg

The results of 81 endorectal flap advancements for simple rectovaginal fistulas are reported. Simple fistulas are defined as <2.5 cm in diameter, low or mid vaginal septum in location, and infectious or traumatic in origin. Essentially, the technique is advancement of a flap of mucosa, submucosa, and circular muscle over midline approximation of internal sphincter muscle. The mean patient age was 34 years old (range, 18 to 76 years). The causes were obstetrical injury (74 percent), perineal infection (10 percent), operative trauma (7 percent), and unknown (8 percent). Overall, the repair was successful in 83 percent of patients. Success correlated with the number of previous repairs,i.e., none: 88 percent success; one: 85 percent success; two: 55 percent success. There were 25 concomitant overlapping sphincteroplasty procedures. Only minor complications ensued, with no mortality. This repair is recommended for patients with no or one previous repair because of its lack of mortality, minimal morbidity, ease of concomitant sphincteroplasty, and avoidance of a colostomy. For patients with two or more earlier repairs, a muscle interposition should be considered.


Journal of Gastrointestinal Surgery | 1998

Cumulative Incidence of Colorectal and Extracolonic Cancers in MLH1 and MSH2 Mutation Carriers of Hereditary Nonpolyposis Colorectal Cancer

Kevin M. Lin; Maniamparampil Shashidharan; Alan G. Thorson; Charles A. Ternent; Garnet J. Blatchford; Mark A. Christensen; Patrice Watson; Stephen J. Lemon; Barbara Franklin; Beth Karr; Jane F. Lynch; Henry T. Lynch

The extracolonic tumor spectrum of hereditary nonpolyposis colorectal cancer (HNPCC) includes cancer of the endometrium, ovaries, stomach, biliary tract, and urinary tract. This study was designed to determine the penetrance of colorectal and extracolonic tumors in HNPCC mutation carriers. Forty-nine patients (22 females and 27 males) were identified with an MSH2 germline mutation, and 56 patients (28 females and 28 males) were identified with an MLH1 mutation. Cumulative incidence by age 60 (lifetime risk) and mean age of cancer diagnosis were compared. The lifetime risk of extracolonic cancers in MSH2 and MLH1 carriers was 48% and 11% respectively (P = 0.016). Extracolonic cancer risk in MSH2 females and males was 69% and 34%, respectively (P = 0.042). Mean age of extracolonic cancer diagnosis was significantly older for MSH2 males than females (55.4 vs. 39.0, P = 0.013). No difference was observed in colorectal cancer risk between MLH1 and MSH2 carriers (84% vs. 71%). Colorectal cancer risk was 96% in MSH2 males compared to 39% in MSH2 females (P = 0.034). No differences in colorectal and extracolonic cancer risks between MLH1 females and males were identified. The risk of extracolonic cancer by age 60 was greater in MSH2 mutation carriers than in MLH1 carriers. Gender differences in colorectal and extracolonic cancer risk were observed for MSH2 carriers only. These phenotypic features of HNPCC genotypes may have clinical significance in the design of genotype-specific screening, surveillance, and follow-up for affected individuals.


Diseases of The Colon & Rectum | 1994

Positron emission tomography for preoperative staging of colorectal carcinoma

P. M. Falk; N. C. Gupta; Alan G. Thorson; M. P. Frick; Bruce M. Boman; Mark A. Christensen; Garnet J. Blatchford

PURPOSE: Positron emission tomography (PET) is an imaging technique based onin vivo cellular metabolism. Increased glucose metabolism in neoplastic cells is detected by using fluorine-18 deoxyglucose. In an ongoing pilot study to determine the usefulness of this technique, PET is compared with computerized tomography (CT) for the preoperative staging of colorectal carcinoma. METHODS: Sixteen patients were evaluated with both PET and CT of the abdomen and pelvis. Results were compared with operative and histopathologic findings. Fifteen malignant lesions were found in 16 patients by histology. PET had a positive predictive value of 93 percent and a negative predictive value of 50 percent. By comparison CT had a positive predictive value of 100 percent and a negative predictive value of 27 percent. CONCLUSIONS: These preliminary results indicate that PET has increased sensitivity for staging colorectal carcinoma, whereas CT has higher specificity. The predictive value of a positive PET compares favorably with CT. Furthermore, the predictive accuracy for detection of colorectal carcinoma is 83 percent for PET and 56 percent for CT.

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Bernard Levin

University of Texas MD Anderson Cancer Center

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Tim Byers

Colorado School of Public Health

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