High incidence combination of multiple primary malignant tumors of the digestive system

BACKGROUND Clinical reports of multiple primary malignant tumors(MPMTs)in the digestive system are increasing.In China,although the survival rate of patients with MPMTs is increasing,the quality of life is very low.Many patients have reached the advanced stage when the second primary tumor is found,resulting in no early intervention and treatment.This is due to the misunderstanding of MPMTs by clinicians,who treat such tumors as metastases.Therefore,before a patient has a second primary tumor,doctors should understand some common combinations of digestive system MPMTs to provide clinical guidance to the patient.AIM To explore the high incidence combination of digestive system MPMTs under heterochronism and synchronization.METHODS A total of 1902 patients with MPMTs at Peking Union Medical College Hospital were analyzed retrospectively.They were divided into metachronous MPMT and synchronous MPMT groups,and then the high incidence combinations of the first primary cancer and the second primary cancer in metachronous cancer and synchronous cancer were sorted.Sex and age differences between metachronous and synchronous tumors were tested by the chi square test and t test,respectively.A P value<0.05 was considered as statistically significant,and SPSS version 26.0(SPSS Inc.,Chicago,Illinois,United States)was used for statistical analysis.RESULTS Among the 1902 patients with MPMTs confirmed by pathology,1811(95.2%)cases were secondary primary cancers,89(4.7%)cases were tertiary primary cancers,and 2(0.1%)cases were quaternary primary cancers.Most(88.2%)of the secondary primary cancers were identified as metachronous multiple primary cancers six months after diagnosis of the first primary cancer.The top ten most common MPMTs in the first primary cancer group ranged from high to low as follows:Breast cancer,thyroid cancer,nonuterine cancer,lung cancer,colon cancer,kidney cancer,uterine cancer,bladder cancer,rectal cancer,and gastric cancer.The highest incidence rate of the first primary cancer in male metachronous cancer was lung cancer(11.6%),the highest incidence rate of the second primary cancer was still lung cancer(24.9%),the highest incidence rate of the first primary cancer in female metachronous cancer was breast cancer(32.7%),and the highest incidence rate of the second primary cancer was lung cancer(20.8%).Among them,breast cancer,nonuterine cancer and uterine cancer were female-specific malignant tumor types,and thyroid cancer also accounted for 79.6%of female patients.The top five metachronous cancer combinations,independent of female-specific malignant tumor types and thyroid cancer,were colon cancer and lung cancer(26 cases),kidney cancer and lung cancer(25 cases),rectal cancer and lung cancer(20 cases),gastric cancer and lung cancer(17 cases),and bladder cancer and lung cancer(17 cases).The most common synchronous cancer combination was colon cancer and rectal cancer(15 cases).CONCLUSION Screening for lung cancer should be performed six months after the detection of colon cancer while rectal cancer screening should be performed within six months.

CHEMOPREVENTION OF LUNG CANCER IN THE HIGH INCIDENCE AREA

Since 1984, mass screening for cancer and chemopreventive trials in the two high incidence areas of lung cancer have been carried out. Chemo preventive trials on the subjects having moderate or severe atypical hyperplasia cells in the sputum were done by treatment with R1 [N-(p-ethoxycarbophenyl) retinamide] and R2 [N-(p-carboxyphenyl) retina-mide]. Results showed that the general status of the patients had improved. IgA and IgM in the serum were increased and the arsenic skin lesions were relieved after the treatment with Rl and R2. The ratio of the incidence of lung cancer for the treated group and the control group was 1:4, and the mean degree of hyperplasia in the sputum had dropped. It is suggested that these drugs are both safe and effective in the chemoprevention of lung cancer.

CONTROL OF UNSTEADY VORTICAL LIFT ON AN AIRFOIL BY LEADING-EDGE BLOWING-SUCTION

The effects of leading-edge blowing-suction on the vortex how past an airfoil at high incidence are investigated numerically by solving the Navier-Stokes equations. The results indicate that the frequency of the flowfield excited by the periodic blowing-suction locks into the forcing frequency, which is half of the dominant frequency for the flow past a fixed airfoil without injection. In that case, a well-developed primary leading-edge vortex occupies the upper surface of the airfoil and the largest lift augmentation is obtained.