Case 1 Mr. Li presented to the hospital with painful swallowing with poor feeding, hoarseness and neck swelling, CT indicated laryngeal occupancy and enlarged lymph nodes in the right neck, and pathology was taken as laryngopharyngeal squamous cell carcinoma. After admission, we learned that the patient had occasional bloody stools during routine history taking, and later the pathology was taken as sigmoid colon cancer after colonoscopy. The patient’s final diagnosis: laryngopharyngeal carcinoma and sigmoid colon cancer. Case 2 Ms. Zhao was treated for a neck swelling that was not effective for tuberculosis and then pathologically confirmed as lymphoma. The final diagnosis of the patient: lymphoma and cervical cancer. Case 3 Master Wang had a cough and hemoptysis for six months, and a lung CT examination revealed a shadow in the upper lobe of the right lung, with pathological findings of squamous lung cancer. During the course of inpatient radiotherapy, he developed hoarseness again, and laryngeal tumor was found by another laryngoscopy, and the pathological diagnosis was laryngeal cancer. The final diagnosis of the patient: lung cancer, laryngeal cancer. Case 4 Ms. Zhao was proposed to undergo thyroidectomy due to thyroid tumor. During the preoperative comprehensive examination, a small amount of pleural fluid was found on lung CT, which gradually increased and a mass of about 1 cm in diameter was found at the bottom of the lung near the diaphragm after pleural fluid aspiration. The pathology of the thyroid gland after surgery was papillary adenocarcinoma, and the pathology of the lung mass was low-grade adenocarcinoma. The final diagnosis of this patient: thyroid adenocarcinoma, lung cancer. Professor Xu Xiangying, director of the quality control center of radiotherapy department in Heilongjiang Province, director of radiotherapy teaching and research department of Harbin Medical University Cancer Hospital and supervisor of doctoral students, introduced that in 2013 alone, four cases of repeat cancer were found and diagnosed among inpatients attending radiotherapy department 1 of Harbin Medical University Cancer Hospital. One of them was found during the routine detailed examination of the whole body after admission to the hospital; the other one was diagnosed after detailed examination again when the patient showed symptoms or signs that did not match with the primary tumor during the treatment of the first tumor. According to Director Xu, with the increasing incidence of tumor and the prolonged survival of tumor patients, the number of patients with double cancer among the tumor patients admitted in recent years has increased compared with previous years. Therefore, it is very important for tumor patients to undergo routine whole-body comprehensive examination when they are admitted to hospital, and lesions or tumors of other parts appearing during treatment should not be easily considered as metastasis of tumor and simply interpreted as monism. Here, it is very important to remind clinicians, especially to draw the attention of colleagues in general hospitals. What exactly is “double cancer”? What is the basis of diagnosis of double cancer? What are the characteristics of double cancer? Director Xu Xiangying summarized for readers the concept, diagnostic criteria, classification, etiology, incidence and prevalence, misdiagnosis and omission, treatment and prognosis of double cancer. I. Concept As the name suggests, multiple primary cancers refer to the occurrence of two or more unrelated malignant tumors (or two or more malignant tumors of different nature occurring in the same patient at the same time or successively) in the same patient, also known as multiple cancers, double primary malignant tumors and duplicated cancers. Some scholars call more than two primary cancers occurring in different parts of the same organ as multiple primary cancers, and primary cancers occurring in more than two organs as duplicated cancers. At present, the diagnostic criteria that have been used at home and abroad for multiple primary cancers are: 1. each tumor must be malignant histologically; 2. each tumor has its own pathological and morphological characteristics; 3. each tumor occurs in different parts or organs and is not continuous with each other; 4. each tumor generally has its unique metastatic pathway; 5. metastatic and recurrent cancers should be excluded in diagnosis. Multiple primary cancers can be divided into “simultaneous multiple primary cancers” and “heterochronic multiple primary cancers” according to the time of onset. 1.Simultaneous multiple primary cancers: it refers to the occurrence of two or more cancers at the same time or within six months. 2.Heterochronic multiple primary cancers: refers to two cancers occurring one after another for more than 6 months. The causes of multiple primary cancers are still unknown, but it is believed that they may be related to the following factors: 1. The continuous effect of carcinogenic factors in patients’ bodies. Cancer patients are often susceptible to infection and more sensitive to carcinogenic factors in the environment. Patients with multiple primary cancers may have susceptibility to certain carcinogenic factors, which may still cause cancer in other parts of the body if the carcinogenic factors are not excluded. Patients who have suffered from certain malignant tumors are 6-12 times more likely to develop new cancers than healthy people. The reason for this is that the same carcinogenic factor is continuously stimulated in pairs of organs and the same system, so cancer is likely to occur simultaneously or successively. 2.Cancer caused by radiation. Radiation therapy for the first primary cancer has long-term side effects, and radiation therapy for cancer has certain carcinogenic and immune function-lowering effects. Diagnostic criteria for second carcinogenesis by radiation therapy: (1) the site of second carcinogenesis must be within the previous irradiation field; (2) there is a fairly long latent period; (3) there is a clear pathological diagnosis. 3.Tumor patients with low immune function. Due to various treatments against tumor, long-term emotional depression, anxiety or long-term use of immunosuppressive drugs, tumor patients may have reduced lymphocytes in blood, and the immune status of the body is also impaired after surgery, radiation therapy and chemotherapy drug treatment after the first primary cancer, and the immune function of the body is reduced. 4. Genetic factors, endocrine factors, application of chemical drugs and multicentricity of cancer are also the reasons for the occurrence of multiple primary cancers. With the rapid development of anti-tumor treatment technology and various treatment methods, the efficacy of malignant tumor treatment has been gradually improved and the survival period of patients has been prolonged, so that later cancers have the opportunity to manifest themselves, making it possible for a new second, third or fourth cancer to occur. According to the literature, the incidence rate of multi-cellular carcinoma is 0.73%-11.7% in foreign countries and 0.35%-0.77% in China. The age of prevalence of multi-cellular carcinoma is 50-70 years old. Among them, head and neck tumors (such as nasopharyngeal cancer and pharyngeal cancer), respiratory system tumors (such as lung cancer) and digestive system (such as colorectal cancer) are more common in men, while breast cancer and female reproductive system tumors (such as endometrial cancer and ovarian cancer) are more common in women. Reasons for missed diagnosis or misdiagnosis Clinically, multiple primary cancers are easily confused with metastasis and recurrence of malignant tumors and are misdiagnosed for the following reasons: 1.Insufficient understanding of multiple primary cancers, the clinical manifestations of second primary cancers are often confused with the first primary cancers or covered by the first primary cancers and are simply considered as metastasis of the primary cancer, so the existence of second primary cancers is not detected. 2.Because there is a difference in the time of onset of multiple primary cancers, and the second cancer of heterochronic multiple primary cancers occurs mostly within 5 years after the treatment of the first cancer, especially within 1~3 years, which coincides with the time of recurrence or metastasis of the first cancer, clinicians often simply consider it as the recurrence or metastasis of the primary tumor without considering the possibility of multiple primary cancers when diagnosing. Although both metastatic cancer and multiple primary cancers manifest as new lesions appearing in the patient’s body, metastatic cancer essentially originates from the primary cancer and its pathological nature is exactly the same as that of the primary cancer; whereas multiple primary cancers are another type of new cancer lesions appearing in the cancer patient’s body and the nature of such cancer lesions is completely different from that of the original lesions, in addition, the primary lesions and metastatic lesions can be initially judged through imaging examinations, such as the CT manifestation of lung cancer, lung Metastatic tumors are mostly in the outer lung zone, with round or round-like shape and clear margins, usually without lobulation, burr sign or satellite foci; primary lung cancer is mostly manifested as a lamellar or isolated mass shadow, often with signs such as lobulation sign, margin burr and uneven density of tumor body. Treatment and prognosis It is generally believed that the treatment effect of multiple primary cancers is better than cancer recurrence or metastasis. And there is a difference in survival between patients with concurrent and heterochronic multiple primary cancers, with the latter being significantly better than the former. Therefore, Director Xu Xiangying of the Department of Radiotherapy of Harbin Medical University Cancer Hospital talked about that early diagnosis and treatment are the main factors affecting the survival of patients with multiple primary cancers, and it is of great clinical significance to distinguish multiple primary cancers from metastatic cancers, because there is a significant difference in the treatment effect between them. Metastatic cancer indicates that the original cancer has progressed to advanced stage, and the treatment effect is generally poor. On the other hand, primary cancer can achieve the same curative effect as the first primary cancer through early diagnosis and active treatment. With the improvement of current anti-tumor treatment technology, the survival period of tumor patients has been prolonged, while the incidence of multiple primary cancers is also on the rise. For this reason, Professor Xu Xiangying, who has been working in a specialized oncology hospital for 30 years, said: as a clinician, you should improve your understanding of multiple primary cancers, reduce misdiagnosis or missed diagnosis, achieve early diagnosis and early treatment, and prolong the survival time of patients. Therefore, when diagnosing, treating and following up malignant tumors in the same organ, clinicians should be highly alert to the existence of second primary malignant tumors in other organs, different parts of the same organ or other systems. Multiple primary cancers are mostly seen in the same organ, digestive system and respiratory system. In conclusion, examination and follow-up of tumors of these organs and systems are especially important, especially for patients with family history of malignant tumors, they should be extra alert to the occurrence of multiple primary malignant tumors.