Primary peritoneal carcinoma

　　1. Etiology

　　The cause of the disease is unknown, and there is still controversy about the source of the tissue. Currently, there are two theories: the malignant transformation of the residual ovarian tissue on the embryonic migration pathway; the peritoneal epithelium and ovarian epithelium originate from the same intermediate germ layer, both derived from the embryonic coelomic epithelium (Embryonal Coelomic Epithelium), with the potential for müllerian differentiation, known as the second müllerian system (Second müllerian system), which becomes cancer after being stimulated by some carcinogen.

　　2. Pathogenesis

　　Since the peritoneum and müllerian duct have a common embryonic origin, and the female reproductive system is derived from the müllerian duct during embryonic development, when certain factors cause primary peritoneal tumors, their tissue structure is consistent with the tumors occurring in the female müllerian duct, but there is no invasion or only superficial micro-invasion on the surface of the ovary. Therefore, some people believe that this type of tumor originating from the primary peritoneum in women is a tumor originating from the 'second müllerian system', which is an independent disease different from ovarian cancer. Since serous adenocarcinoma accounts for the majority of primary peritoneal tumors, the so-called müllerian tumors in women mainly refer to serous adenocarcinoma occurring in the peritoneum, that is, extra-ovarian peritoneal serous papillary cancer.

　　A small number of patients have pleural effusion, and in the late stage, systemic symptoms may appear, such as weight loss and cachexia. The biological behavior of this disease is similar to that of advanced ovarian cancer.

　　The pleural cavity is a closed space composed of the parietal pleura and visceral pleura, which is under negative pressure. Normally, there is a small amount of fluid (about 1~30 milliliters) between the two pleural layers, which acts as a lubricant to reduce friction between the two pleural layers during respiratory activities, benefiting the expansion and contraction of the lungs within the pleural cavity. This fluid is produced by the parietal pleura, absorbed by the visceral pleura, and continuously circulates in a dynamic balance, maintaining a constant volume. When something affects the pleura, whether it is the production of pleural effusion by the parietal pleura or the change in the rate of absorption of pleural effusion by the visceral pleura, it can cause an increase in the fluid in the pleural cavity, which is what is called pleural effusion (accumulation of fluid).

　　Ovarian cancer is a malignant tumor of ovarian tumors, referring to the malignant tumor growing on the ovary. Among them, 90% to 95% are primary ovarian cancers, and another 5% to 10% are cancers originating from other parts that have metastasized to the ovary.

　　The onset of the disease is slow and insidious, with no自觉 symptoms in the early stage. Clinical symptoms appear when the tumor grows to a certain size or affects other organs, with abdominal pain, distension, and increased abdominal circumference being the most common three symptoms. The abdominal pain is not severe, only a feeling of abdominal distension or discomfort is felt, and the main sign is an abdominal mass and ascites. The abdominal mass is often large, with unclear boundaries, and the ascites increases rapidly, mostly being hemorrhagic.

　　1. Do not drink alcoholic beverages for a long time, quit smoking and drinking habits, and do not overeat pickled, sour, spicy, and刺激性 food. Ban eating moldy food. It is more important for those with chronic pharyngitis to develop good dietary hygiene habits, such as eating less meat and more vegetables, and eating more fresh fruits and vegetables.

　　In cold seasons, maintain appropriate temperature and humidity indoors and pay attention to air circulation. The room temperature should be around 20℃, and do not cover yourself too heavily during sleep at night to avoid excessive temperature or dryness, which may cause discomfort in the throat. Do not sleep with the wind and rest for a while after strenuous labor, and do not take a cold shower immediately. For those with acute pharyngitis caused by common cold, drink more hot water or ginger soup to sweat and increase urine excretion. Pay attention to smooth defecation. Treat acute inflammation in a timely manner to prevent it from becoming chronic. Organs with chronic lesions are more prone to malignant transformation.

　　1. Cytological examination:Abdominal fluid is collected for cytological examination by laparoscopic puncture or posterior fornix puncture through the vagina, and malignant tumors are often positive.

　　2. Peritoneal biopsy:Peritoneal biopsy is of great value in the diagnosis of peritoneal tumors and can be performed by biopsy under laparoscopic vision or by laparotomy to explore peritoneal biopsy.

　　3. Immunohistochemistry:The immunohistochemical characteristics are similar to those of ovarian serous carcinoma, with positive mucin determination and Schiff's periodic acid-Schiff staining. No hyaluronic acid is produced. Wei et al. measured the immunohistochemical indicators of peritoneal serous carcinoma, including single-antigen keratin, epithelial cell membrane antigen, CA125 antigen, LeuM1, B72.3 antigen, carcinoembryonic antigen, amylase, LN1, LN2, MB2, S-100 protein, and placental alkaline phosphatase, all of which were positive. Zhou et al. reported that all cases were positive for EMA and S-100 protein, 75% of the cases were positive for CA125, 88% were positive for CD15, and 38% were positive for placental alkaline phosphatase.

　　4. Ultrasound:The main examination for diagnosis, which can suggest the location, size, shape, and nature of the tumor, and is helpful in distinguishing ovarian cancer from peritoneal cancer.

　　5. CT examination:It can clearly show masses, ascites, and lymph node metastasis.

　　6. Laparoscopic examination:It is possible to clearly see the nature, size, location, and whether there is peritoneal metastasis, and abdominal fluid and biopsy can be collected for corresponding examination.

　　In daily life, attention should be paid to reasonable nutrition, and food should be as varied as possible. Eat more high-protein, high-vitamin, low-animal-fat, easily digestible foods, fresh fruits and vegetables, and avoid eating stale, deteriorated, or刺激性 food. Eat less smoked, roasted, pickled, fried, or overly salty food. Combine coarse and fine grains in staple foods to ensure nutritional balance. The tumor itself is the most important, with diet serving as an auxiliary.

　　1. Treatment

　　1. The surgical resection of this disease should strive for complete resection of the tumor. For those who cannot be completely resected, debulking surgery (Debulking Surgery) should be performed to strive for residual tumor within 2cm. It must be emphasized that bilateral ovaries should be simultaneously removed to observe the condition of ovarian lesions.

　　2. Chemotherapy The chemotherapy drugs are not standardized yet, and the ovarian cancer regimen is preferred, that is, the regimen mainly using cisplatin (DDP): such as PAC or CP regimen.

　　Second, Prognosis

　　The biological behavior of this disease is similar to that of advanced ovarian cancer, and previous reports showed poor prognosis. With the application of chemotherapy regimens mainly using cisplatin, the prognosis has significantly improved. The 2-year survival rate of female serous peritoneal cancer at Tianjin Cancer Hospital is 33%, Zhang Guiyu's 11 cases had an average survival of 171 months, and it is believed that the prognosis is not worse than that of concurrent serous ovarian cancer.

　　Foreign reports show varying average survival periods, Ransom reported 17 months, among which 3 cases survived for 6 to 7 years, all of whom received 6 to 12 courses of chemotherapy (DDP 60mg/m2, cyclophosphamide 1000mg/m2, on the first day, 4 weeks as one course) after satisfactory debulking surgery. Dalrymple believed that peritoneal cancer has no difference in prognosis with stage III-IV ovarian cancer, with a median survival period of 11.3 months, Truong reported 14.7 months, Zhou reported 27 months, the 5-year survival rate was 27% (10 cases), Mulhollan (87 cases) reported 17 months, the 2-year survival rate was 28%, and Rothacker (57 cases) reported a 1-year survival rate of 0.

　　Fromm summarized the median survival period of 24 months (74 cases) and believed that the survival period is not related to the patient's age and the size of the residual tumor, the number of papillae, but rather the presence of mitosis affects its prognosis. The median survival period of patients receiving regular combined chemotherapy is 29.5 months, 16.5 months for a single course of chemotherapy, and 31.5 months for chemotherapy mainly using cisplatin, which is significantly higher than the 19.5 months of the group not using cisplatin, and the median survival period of chemotherapy with cyclophosphamide plus cisplatin is 34.5 months.

　　Ben observed and compared peritoneal serous papillary carcinoma and stage III-IV ovarian serous carcinoma, and found no statistically significant differences (average age, menopausal status, number of deliveries, amount of ascites, and proportion of patients receiving satisfactory debulking surgery). The average tumor-free interval is 15 and 18 months, the average survival period is 21 and 26 months, the 5-year survival rate is 18% and 24%, and the median survival period with residual tumor ≥2cm is 20.5 and 24 months, and ≤2cm is 46 and 41 months.