1. NAACCR/IACR Combined Annual Conference 2019
Treatment of Stage IV Colon Cancer in the US: A Patterns of Care Analysis
Xiang Gao1, Amanda Kahl2 , Paolo Goffredo1, Imran Hassan1, Mary Charlton2
1University of Iowa, Department of Surgery; 2University of Iowa, College of Public Health
NAACCR/IACR Combined Annual Conference 2019

2. Disclosures
The authors have nothing to disclose

3. Background - Colon Cancer
3rd most common cancer diagnosis
3rd leading cause of cancer-related deaths
Lifetime risk
Men: 1 in 22
Women: 1 in 24
Stage IV 5-year survival: 14%
77-90% present with unresectable disease
Source: American Cancer Society.

4. Background - SEER POC 2014

5. Background - Stage IV Treatment
Tumor resection, metastasectomy, neo/adjuvant chemotherapy
Chemotherapy + biologics, then re-evaluate
Chemotherapy + biologics
Chemotherapy + biologics
Colon resection if: imminent risk of obstruction, significant bleeding, perforation, or other significant tumor symptoms

6. Objective
Examine the patient, tumor, and hospital factors associated with treatment regimens in stage IV colon cancer.

7. Methods - Study Population
Patients aged >20 years
Diagnosed in 2014
Stage IV colon- first and only cancer
Sampling proportionate to registry size
Connecticut, New Jersey, Iowa, Detroit, Kentucky, Louisiana, Atlanta, California, Hawaii, New Mexico, Seattle, Utah
Oversampling of racial minorities

8. Methods - Treatment Variables
Primary tumor resection (PTR, yes/no)
Radiation (yes/no)
Chemotherapy
Targeted biologic agents
Treatment groups:
Resection plus chemotherapy
Chemotherapy only
Given within 7 weeks of diagnosis
Resection only
No treatment

9. Methods - Additional Variables
Charlson Index
SEER Registry region:
Northeast: Connecticut, New Jersey
North Central: Iowa, Detroit
South: Kentucky, Louisiana, Atlanta
West: California, Hawaii, New Mexico, Seattle, Utah

10. Methods - Statistical Analysis
Treatment patterns by SEER region
Chi-square tests
Patient, tumor, hospital/region characteristics by treatment
Multinomial logistic regression
Patient, tumor, hospital/region characteristics by treatment with chemotherapy only as reference group
Overall survival
Kaplan-Meier
Cox proportional hazards

11. Results
SEER 18 Registry POC patients diagnosed with stage IV colon cancer in 2014
(N=1445)
Exclude histologies that are not
malignant neoplasm, carcinoma, adenocarcinona, mucinous adenocarcinoma, or signet ring cell carcinoma
N=38
Stage IV adenocarcinoma of colon
(N=1407)

12. Resection + Chemotherapy
Results - Overall Population
Total: 3336 weighted cases
Mean age: 63
Male: 51%
White: 63%
Resection + Chemotherapy
41%
Resection first
73%
Chemotherapy first
13%
Unknown sequence
14%
Chemotherapy Only
23%
Resection Only
16%
No treatment
17%
Surgery to metastasis
28%

13. Results - Patterns of Treatment by Region

14. Residency program status
Results - Univariable Analysis by Treatment Group
Patient Demographics
Age at diagnosis
Sex
Race
Insurance status
Marital status
Clinical characteristics
Charlson Index
Perforation
Obstruction
Hospital/registry characteristics
Registry Region
Hospital bed size
Residency program status
Treatment variables
PTR and chemotherapy sequence
Surgery to metastasis
Radiation
Chemotherapy
VEGF inhibitor
EGFR inhibitor
Tumor characteristics
Histology
Grade
T, N, M stages
KRAS, BRAF status
MSI

15. Results - Multinomial Regression
Factors associated with PTR + Chemotherapy (vs chemotherapy only)

16. Results - Multinomial Regression
Factors associated with PTR only (vs chemotherapy only)

17. Factors associated with no treatment (vs chemotherapy only)
Results - Multinomial Regression
Factors associated with no treatment (vs chemotherapy only)

18. Results - Kaplan Meier Overall Survival
Median survival
PTR + Chemotherapy: >24 months
Chemotherapy Only: 14 months
PTR only: 5 months
No treatment: 2 months

19. Results - Cox Proportional Hazards
Adjusted for: Age, sex, race, insurance status, marital status, Charlson Index, SEER region, hospital bed size, hospital residency status, tumor histology, grade, T, N, and M stages, KRAS, BRAF, MSI, perforation, obstruction, surgery to metastasis

20. Summary PTR + Chemo PTR only No treatment Node positive
Lower metastatic burden
+ perforation
+ obstruction
Married
Small, non-academic hospitals
PTR only
Advanced T, N
Lower metastatic burden
+ perforation
+ obstruction
Older
Medicaid
Small hospitals
No treatment
Unknown genetic markers
Older
African American
57% of patients received PTR (+/- chemotherapy)

21. Conclusions
Resection is frequently used in treatment of stage IV colon cancer
Resection should be reserved to severe symptoms or curative intent
Variation in treatment patterns by hospital factors
Support for guideline implementation may be particularly beneficial in small, non-academic hospitals
Variation in treatment patterns by race, insurance status, age
Efforts that identify/address barriers to care, patient education

22. Thank you