2. Age The median age of HL patients at diagnosis was 26 ~ 3 1 year. The peak of 1 in HL patients is at the age of 20 ~ 29 at first, and the second peak is over 60 years old. At present, it has been confirmed that the second peak of the disease is due to the wrong pathological classification. According to the latest data from SEER (Surveillance, Epidemiology and Final Results Program) of American Cancer Institute, most misclassified cases are non-Hodgkin's lymphoma (NHL), not mixed-cell HL or lymphopenic HL. Generally speaking, tuberous sclerosis (NS) is the most common type. More than 70% of cases are under 40 years old, and there is no second peak. The incidence of other histological subtypes, such as lymphocyte dominant type, mixed cell type and lymphopenia (LD), is low, but it gradually increases with age.
3. The incidence of male HL is about 1.4 times that of female HL. The incidence of male patients is higher than that of female patients, mainly children under 10 and elderly people in their fifties. /kloc-female patients between 0/0 and 40 years old are dominant, because this age group is the peak of NSHL, and female NSHL is more common than male NSHL.
4. Ethnic HL is mainly a malignant tumor of whites in the United States, and whites account for more than 90% of all HL cases.
5. The etiology of risk factor h 1 is still unclear. Now it is considered to be related to genetic susceptibility and infection, especially EB virus infection and HL. Current epidemiological data support the above two causes, but the genetic susceptibility and HL subtype caused by infection are different.
(1) Infection factors:
①EB virus infection: most HL cases in developing countries are EBV positive, and about 40% ~ 50% HL cases in developed countries are related to EBV infection. These cases are mainly children and the elderly, but rare in young patients with tuberous sclerosis HL. For example, in Kenya, 100% of children's cases are positive for EBV latent membrane protein-1 (latent membrane protein-1LMP- 1), and 25 of them have EBV virus types I and/or II in this study. Only 63% of Kenyan adults are positive for LMP-1. The recent epidemiological analysis of 1546 cases of HL showed that the positive rate of EBV in mixed cell type was significantly higher than that in tuberous sclerosis type, and that in children was significantly higher than that in young men, Hispanics and whites.
In 2000, there were about 7,500 new cases of HL in the United States, a decrease of about 16% since the 1970s. Japan studied the positive rate of EBV in HL from 65,438+0,955 to 65,438+0,999, and found that the total positive rate of EBV decreased gradually with the development of time. 52% (1955 ~ 1969), 46% (1970 ~1984),1985 ~ 65485. Interestingly, the positive rate of tuberous sclerosis EBV decreased significantly. From 1970 to 1984 to 2 1%, from 1985 to 1999. The positive rate of EBV is influenced by socio-economic status and ethnic genetic background to some extent. In the past few decades, Japan's living standards have improved significantly, and its lifestyle has also undergone great changes, from tradition to the west. Therefore, in non-industrialized countries and early industrialized countries, the EBV positive rate of HL may decrease with the progress of industrialization.
When EBV exists in HL patients, the monoclonal EBV genome can be detected in all tumor cells. However, not all HL patients are EBV-positive, and the role of EBV virus in lymphatic malignant tumors needs further study.
② HIV: HL is the most common AIDS-related tumor among HIV-positive people, and the incidence of HL among HIV-infected people is about 7 times higher. At present, more than 300 cases of HIV infection in HL have been reported, mainly in European countries (such as Italy, Spain and France), less in the United States, and even less in Asian countries such as Japan and China. The risk of HL in HIV-infected patients increases, and the histological type, biological behavior and prognosis of HL in this population are very different from those in other non-HIV-infected HL patients. HIV-positive and advanced HL patients usually have extranodal lesions. The prognostic factors of these patients are usually related to HIV, not HL. Compared with non-HIV-infected HL patients, HIV-infected HL patients have lower response rate to chemotherapy, higher recurrence rate, more infection complications and lower overall survival rate. Unlike non-HIV-infected HL patients, EBV is positive in most HIV-related HL cases (accounting for 80% ~ 90%). In Reed-Sternberg cells, the LMP- 1 of EBV is highly expressed, and as a tumor necrosis factor receptor-like molecule, it is continuously activated, which leads to the activation of signal pathways that promote cell activation, growth and survival, and finally forms the above-mentioned HIV-related HL- specific bad characteristics.
(2) Genetic tendency: The study of twins confirmed that the risk of identical twins suffering from HL was significantly higher than that of fraternal twins. However, generally speaking, the incidence of familial HL is less than 5% in all HL patients. A retrospective analysis of 328 cases of familial HL showed that the peak of onset was 15 ~ 34 years old, and the sporadic onset age curve of HL was wide. In the study of 60 cases of HL patients from different families, EBV or EBV seropositivity was not found in tumor tissues of all patients in the same family, and only 65438 pairs of identical twins were found in 10. These data indicate that EBV does not play a major role in the pathogenesis of familial HL.
(3) Others: Other risk factors include exposure to herbicides and certain occupations, such as carpentry, animal husbandry and meat processing. In addition, the incidence of HL is also affected by socio-economic conditions. Those who come from high-level families or small families with higher education are at higher risk of developing HL. In economically backward countries and regions, the incidence of HL in children and adolescents is also higher than that in economically developed countries and regions.