Risk of colon cancer-related death in people who had cancer in the past.

BACKGROUND: The rate of second primary malignancies (SPM) is gradually increasing. Yet, the risk of death from primary cancer vs. SPM is still not well understood. In this study, we investigated the survival of patients with colorectal cancer (as SPM) who had cancer in the past (prior cancer) and the risk factors of SPM death in this population. MATERIALS AND METHODS: Based on the Surveillance, Epidemiology, and End Results (SEER) database, we identified 1866 colon cancer patients with prior cancer in our main cohort and 43,959 colon cancer patients, including 37,440 patients with colon cancer as only malignancy and 6519 patients with colon cancer as subsequent colon cancer (SCC), in a second cohort and 3429 colon cancer patients, including 2371 patients with prior colon cancer (PCC) and 1058 patients with colon cancer as SPM, in a third cohort. After propensity score matching, 6519 pairs of subjects were identified in second cohort. RESULTS: Patients with prior prostate and breast cancer had a higher risk of developing colon cancer compared to those with gastrointestinal cancer. Also, colon cancer patients with different prior cancer had different survival rates. Furthermore, except for prior lung cancer (52.78 vs. 25.93%), most subjects died due to colon cancer complications. The ratio of colon cancer deaths to prior cancer deaths in patients with a low stage and high stage was 1.51 and 6.64, respectively. In addition, colon cancer-specific survival (CSS) and OS rates were significantly lower in subjects with colon cancer as the SPM than in those with PCC. Also, compared with PCC, SPM was associated with OS and CSS with HR 1.59 (95 CI 1.43-1.78) and HR 2.00 (95% CI 1.70-2.36). Furthermore, compared with only colon cancer, SCC was associated with OS and CSS with HR 1.23 (95 CI 1.17-1.29) and HR 1.13 (95% CI 1.06-1.21). CONCLUSIONS: Prior cancer was found to have an adverse impact on OS in patients with colon cancer (secondary cancer), most of whom died due to colon cancer as secondary cancer itself rather than prior cancer. Early detection and treatment strategies should be investigated in this population.

External dc bias-field effects in the nonlinear ac stationary response of dipolar particles in a mean-field potential.

External dc bias-field effects on the nonlinear dielectric relaxation and dynamic Kerr effect of a system of permanent dipoles in a uniaxial mean-field potential are studied via the rotational Brownian motion model postulated in terms of the infinite hierarchy of differential-recurrence equations for the statistical moments f_{n}(t)=〈P_{n}〉(t) (the expectation value of the Legendre polynomials P_{n}). By solving these equations, the nonlinear dielectric and Kerr-effect ac stationary responses are evaluated for arbitrary dc field strength via perturbation theory in the ac field. Simple analytic equations based on the large separation of the time scales of the fast intrawell and slow overbarrier (interwell) relaxation processes are also derived.