Lung cancer is the leading cause of cancer-related death globally and in China, classified into two major subtypes: non-small cell lung cancer (NSCLC, 80-85% of cases, including adenocarcinoma, squamous cell carcinoma, and large cell carcinoma) and small cell lung cancer (SCLC, 15-20% of cases, highly aggressive and neuroendocrine-derived).

• Etiology: Tobacco smoking is the dominant risk factor (responsible for ~85% of cases), with additional contributors including ambient air pollution, occupational carcinogen exposure, family history, chronic obstructive pulmonary disease (COPD), and radon exposure. East Asian patients with lung adenocarcinoma have a significantly higher rate of targetable driver mutations (50-60% EGFR mutation rate, vs. 10-15% in Western populations).
• Clinical Manifestations: Early-stage lung cancer is mostly asymptomatic. Advanced disease presents with persistent cough, hemoptysis, chest pain, dyspnea, unintended weight loss, hoarseness, and paraneoplastic syndromes. Brain and bone metastases are common at late stages.
• Diagnosis: Low-dose computed tomography (LDCT) is the gold standard for population-based screening. Definitive diagnosis requires histopathological confirmation via biopsy, with enhanced chest CT and PET-CT for staging. Comprehensive molecular profiling (EGFR, ALK, ROS1, KRAS, MET, RET, etc.) is mandatory for advanced NSCLC to guide targeted therapy.

• Early-Stage NSCLC (Stage I-II): Surgical resection is the curative gold standard, with video-assisted thoracoscopic surgery (VATS) and robotic-assisted thoracic surgery (RATS) as the first-line minimally invasive approaches. Adjuvant chemotherapy, targeted therapy, or immunotherapy is indicated for high-risk patients.
• Locally Advanced NSCLC (Stage III): For resectable disease, neoadjuvant chemoimmunotherapy followed by surgery and adjuvant therapy is standard.
• Advanced/Metastatic NSCLC (Stage IV): Precision therapy is the core of management. For driver mutation-positive disease, tyrosine kinase inhibitors (TKIs) are first-line. For driver-negative disease, chemotherapy combined with immune checkpoint inhibitors (ICIs) or dual immunotherapy is standard.
• SCLC: For limited-stage disease, concurrent chemoradiotherapy plus prophylactic cranial irradiation (PCI) is standard. For extensive-stage disease, first-line treatment is platinum-based chemotherapy combined with ICIs.

Breast cancer is the most commonly diagnosed malignancy in women globally and in China, classified by histology (invasive ductal carcinoma, 70-80% of cases; invasive lobular carcinoma, 10-15%) and molecular subtypes: Luminal A, Luminal B, HER2-positive, and triple-negative breast cancer (TNBC).

• Etiology: Key risk factors include prolonged estrogen exposure (early menarche, late menopause, nulliparity, late first birth, no breastfeeding), germline BRCA1/2 mutations, family history, obesity, excessive alcohol intake, and hormone replacement therapy. Over 70% of Chinese women have dense breast tissue, which reduces the sensitivity of mammography for early detection.
• Clinical Manifestations: The most common presentation is a painless, palpable breast lump. Additional signs include nipple discharge, retraction, skin dimpling/peau d'orange change, axillary lymphadenopathy, and breast pain. Advanced disease presents with bone pain, dyspnea, weight loss, and neurological deficits from distant metastases.
• Diagnosis: Breast ultrasound is the first-line screening and diagnostic modality in China, optimized for dense breast tissue. Mammography, breast MRI, and image-guided core needle biopsy (the gold standard for histopathological diagnosis) are used for further evaluation. Mandatory testing includes hormone receptor (ER/PR), HER2, Ki-67, and germline BRCA testing for high-risk patients.

• Early-Stage Breast Cancer (Stage I-II): Surgical resection is the curative foundation, with breast-conserving surgery (BCS) plus whole-breast radiotherapy, or total mastectomy with sentinel lymph node biopsy (SLNB) to avoid unnecessary axillary lymph node dissection (ALND). Adjuvant therapy is stratified by subtype: endocrine therapy for Luminal disease, anti-HER2 targeted therapy plus chemotherapy for HER2-positive disease, and chemotherapy with or without immunotherapy for high-risk TNBC.
• Locally Advanced Breast Cancer (Stage III): Neoadjuvant systemic therapy (chemotherapy, targeted therapy, endocrine therapy, or immunotherapy) followed by surgery and adjuvant therapy is the standard of care to improve resectability and breast conservation rates.
• Advanced/Metastatic Breast Cancer (Stage IV): Systemic therapy is the core of management. For Luminal disease, endocrine therapy combined with CDK4/6 inhibitors is first-line. For HER2-positive disease, dual anti-HER2 targeted therapy with chemotherapy is standard. For TNBC, chemotherapy combined with ICIs (for PD-L1-positive disease) or antibody-drug conjugates (ADCs) is first-line. Local radiotherapy and surgery are used for palliative symptom control.

Primary liver cancer is the second leading cause of cancer-related death in China, with hepatocellular carcinoma (HCC) accounting for 85-90% of cases, followed by intrahepatic cholangiocarcinoma (ICC) and mixed hepatocellular-cholangiocarcinoma.

• Etiology: Over 80% of HCC cases in China are caused by chronic hepatitis B virus (HBV) infection, with additional risk factors including hepatitis C virus (HCV) infection, alcoholic liver disease, non-alcoholic steatohepatitis (NASH), aflatoxin exposure, cirrhosis, and hereditary liver disease.
• Clinical Manifestations: Early-stage HCC is almost entirely asymptomatic. Intermediate and advanced disease presents with right upper quadrant pain, abdominal distension, anorexia, unintended weight loss, jaundice, ascites, and lower extremity edema. Terminal disease presents with hepatic failure, variceal bleeding, and encephalopathy. Lung and bone are the most common distant metastatic sites.
• Diagnosis: Abdominal ultrasound combined with serum alpha-fetoprotein (AFP), AFP-L3, and PIVKA-II is the standard for biannual screening in high-risk patients (chronic HBV/HCV carriers, cirrhosis patients). Contrast-enhanced CT/MRI with LI-RADS scoring is the gold standard for non-invasive clinical diagnosis of HCC (no biopsy required for typical lesions). Liver biopsy is reserved for indeterminate lesions. Staging is primarily based on the BCLC (Barcelona Clinic Liver Cancer) system, with mandatory HBV/HCV viral load testing and Child-Pugh liver function assessment.

• Very Early/Early-Stage HCC (BCLC 0-A): Curative therapies are the standard of care, including surgical resection, liver transplantation, and thermal ablation (radiofrequency ablation [RFA] or microwave ablation [MWA]). These treatments achieve a 5-year OS rate of over 70%.
• Intermediate-Stage HCC (BCLC B): Transarterial chemoembolization (TACE) is the gold standard, with combination therapies (TACE + ablation, TACE + targeted therapy/immunotherapy) recommended for high-burden disease.
• Advanced-Stage HCC (BCLC C): Systemic therapy is the core of management. The first-line standard of care is immune checkpoint inhibitor combined with anti-angiogenic therapy. Multi-target TKIs are alternative first-line options. Locoregional therapies including TACE, HAIC, and radiotherapy are used as adjunctive treatment.
• Terminal-Stage HCC (BCLC D): Best supportive care, symptomatic management, and palliative interventions are the mainstay, with liver transplantation considered for strictly selected patients.

• Etiology: Helicobacter pylori (Hp) infection is the dominant risk factor. Additional risk factors include high-salt diet, pickled/smoked food intake, tobacco smoking, excessive alcohol consumption, family history, precancerous lesions (atrophic gastritis, intestinal metaplasia, dysplasia), and hereditary cancer syndromes (Lynch syndrome, familial adenomatous polyposis [FAP]).
• Clinical Manifestations: Early gastric cancer is mostly asymptomatic or presents with non-specific dyspepsia. Advanced disease presents with persistent epigastric pain, anorexia, unintended weight loss, melena, hematemesis, iron-deficiency anemia, and abdominal mass. Terminal disease presents with gastric outlet obstruction, jaundice, ascites, and distant metastases (most commonly to peritoneum, liver, and lymph nodes).
• Diagnosis: Gastroscopy with biopsy is the gold standard for definitive diagnosis, with chromoendoscopy, narrow-band imaging (NBI), and magnifying endoscopy widely used for early cancer detection. Hp testing is mandatory for all patients. Contrast-enhanced CT, endoscopic ultrasound (EUS), and PET-CT are used for staging. Mandatory molecular testing includes HER2, MSI/MMR, and PD-L1 expression. Staging follows the AJCC TNM system.

• Early Gastric Cancer (Stage I): Endoscopic resection (endoscopic mucosal resection [EMR] or endoscopic submucosal dissection [ESD]) is the curative standard for lesions meeting strict indications, preserving gastric function and quality of life. Radical gastrectomy with D2 lymph node dissection is indicated for lesions not eligible for endoscopic resection, with adjuvant chemotherapy for high-risk patients.
• Locally Advanced Gastric Cancer (Stage II-III): Radical D2 gastrectomy is the surgical gold standard. Perioperative chemotherapy (neoadjuvant chemotherapy followed by adjuvant chemotherapy) or postoperative adjuvant chemotherapy is the standard of care to improve R0 resection rate and long-term survival. Neoadjuvant/adjuvant targeted therapy is indicated for HER2-positive disease, and immunotherapy for MSI-H/dMMR disease.
• Advanced/Metastatic Gastric Cancer (Stage IV): Systemic therapy is the core of management. For HER2-positive disease, first-line treatment is chemotherapy plus trastuzumab with or without ICIs. For HER2-negative disease, first-line treatment is chemotherapy plus ICIs for PD-L1-positive patients. Palliative surgery, radiotherapy, and stent placement are used for symptom control of obstruction, bleeding, and pain.

• Etiology: Over 85% of CRC arises from adenomatous polyps (precancerous lesions). Key risk factors include inflammatory bowel disease (ulcerative colitis, Crohn’s disease), hereditary cancer syndromes (Lynch syndrome, FAP), high-fat low-fiber diet, obesity, sedentary lifestyle, tobacco smoking, excessive alcohol intake, and type 2 diabetes.
• Clinical Manifestations: Early CRC is mostly asymptomatic. Colon cancer commonly presents with abdominal pain, changes in bowel habits, melena, iron-deficiency anemia, unintended weight loss, and bowel obstruction. Rectal cancer presents with hematochezia, tenesmus, changes in stool caliber, and rectal bleeding. Advanced disease presents with bowel obstruction, ascites, jaundice, and distant metastases (most commonly to the liver and lungs).
• Diagnosis: Colonoscopy with biopsy is the gold standard for definitive diagnosis. Fecal occult blood test (FOBT) and fecal DNA testing are used for population-based screening. Contrast-enhanced CT, pelvic MRI (for rectal cancer staging), EUS, and PET-CT are used for staging. Mandatory molecular testing includes RAS, BRAF, MSI/MMR, and HER2 status. Staging follows the AJCC TNM system.

• Precancerous Lesions/Early CRC (Stage 0-I): Endoscopic resection (EMR/ESD) is the curative standard for adenomas and intramucosal carcinoma. Radical surgical resection (laparoscopic colectomy for colon cancer, total mesorectal excision [TME] for rectal cancer) is indicated for lesions not eligible for endoscopic resection, with no adjuvant therapy required.
• Locally Advanced CRC (Stage II-III): For colon cancer, radical colectomy followed by adjuvant chemotherapy is the standard for high-risk stage II and all stage III disease. For mid-to-low rectal cancer, neoadjuvant chemoradiotherapy (long-course or short-course radiotherapy) followed by TME surgery and adjuvant chemotherapy is the standard, to improve sphincter preservation rate and reduce local recurrence.
• Advanced/Metastatic CRC (Stage IV): Systemic therapy is the core of management, guided by molecular profiling. For resectable liver/lung metastases, surgical resection of the primary tumor and metastases plus perioperative systemic therapy is the standard, with conversion therapy for initially unresectable disease to achieve resectability. Palliative surgery and radiotherapy are used for symptom control.

Nervous system tumors are classified into primary central nervous system (CNS) tumors (intracranial and intraspinal tumors) and metastatic CNS tumors (brain metastases, the most common intracranial tumors, accounting for 20-40% of all intracranial neoplasms). Primary intracranial tumors are dominated by gliomas (40-50% of primary intracranial tumors, WHO grade I-IV, with grade IV glioblastoma [GBM] being the most malignant), meningiomas (20-30%, mostly benign), pituitary adenomas (10-15%, mostly benign), vestibular schwannomas (5-8%, benign), medulloblastomas (the most common malignant pediatric brain tumor), germ cell tumors, and craniopharyngiomas.

• Etiology: The etiology of most primary CNS tumors is unknown, with confirmed risk factors including ionizing radiation, hereditary tumor syndromes (neurofibromatosis, von Hippel-Lindau syndrome, Lynch syndrome), and immunodeficiency. Brain metastases most commonly originate from lung cancer, breast cancer, melanoma, and gastrointestinal malignancies.
• Clinical Manifestations: The most common presenting symptoms are increased intracranial pressure (headache, vomiting, papilledema), focal neurological deficits (limb weakness, sensory loss, aphasia, ataxia, visual/hearing loss), and seizures. Pituitary adenomas present with endocrine symptoms (amenorrhea, galactorrhea, acromegaly, Cushing syndrome). Pediatric brain tumors commonly present with hydrocephalus, gait instability, and developmental delay.
• Diagnosis: Contrast-enhanced cranial/spinal MRI is the gold standard for diagnosis and localization. CT is used to evaluate calcification and bony changes. PET-CT is used for systemic staging and detecting metastases. Histopathological confirmation via surgical or stereotactic biopsy is the gold standard for diagnosis and WHO grading. Mandatory molecular profiling includes IDH1/2 mutation, 1p/19q codeletion, MGMT promoter methylation, TERT promoter mutation, and H3 K27M mutation for gliomas, as well as endocrine hormone testing for pituitary adenomas.

• Gliomas: For low-grade gliomas (WHO I-II), maximal safe surgical resection is the standard, with adjuvant radiotherapy/chemotherapy for high-risk patients. For high-grade gliomas (WHO III-IV, anaplastic glioma, GBM), the standard of care is maximal safe surgical resection followed by concurrent chemoradiotherapy with temozolomide and adjuvant temozolomide (Stupp regimen). Recurrent disease is managed with repeat surgery, re-irradiation, chemotherapy, tumor treating fields (TTFields), targeted therapy, immunotherapy, and clinical trials.
• Meningiomas: For asymptomatic small WHO grade I meningiomas, active surveillance is standard. For symptomatic or growing tumors, gross total surgical resection (Simpson grade I) is curative, with a 10-year recurrence rate of <10%. Stereotactic radiosurgery (SRS, gamma knife) is indicated for residual/recurrent tumors, small tumors, or patients unfit for surgery. For atypical/anaplastic meningiomas (WHO II-III), surgical resection plus adjuvant radiotherapy is standard.
• Pituitary Adenomas: For prolactinomas, medical therapy with dopamine agonists (bromocriptine, cabergoline) is first-line. For all other functional adenomas and non-functional adenomas with mass effect, transsphenoidal endoscopic resection is the surgical gold standard, with adjuvant radiotherapy and medical therapy for residual/recurrent disease.
• Vestibular Schwannomas: Gross total surgical resection with facial and cochlear nerve preservation is the curative standard. SRS (gamma knife) is indicated for small tumors, residual/recurrent disease, or patients unfit for surgery.
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Primary liver cancer is the second leading cause of cancer-related death in China, with hepatocellular carcinoma (HCC) accounting for 85-90% of cases, followed by intrahepatic cholangiocarcinoma (ICC) and mixed hepatocellular-cholangiocarcinoma.

• Etiology: Over 80% of HCC cases in China are caused by chronic hepatitis B virus (HBV) infection, with additional risk factors including hepatitis C virus (HCV) infection, alcoholic liver disease, non-alcoholic steatohepatitis (NASH), aflatoxin exposure, cirrhosis, and hereditary liver disease.
• Clinical Manifestations: Early-stage HCC is almost entirely asymptomatic. Intermediate and advanced disease presents with right upper quadrant pain, abdominal distension, anorexia, unintended weight loss, jaundice, ascites, and lower extremity edema. Terminal disease presents with hepatic failure, variceal bleeding, and encephalopathy. Lung and bone are the most common distant metastatic sites.
• Diagnosis: Abdominal ultrasound combined with serum alpha-fetoprotein (AFP), AFP-L3, and PIVKA-II is the standard for biannual screening in high-risk patients (chronic HBV/HCV carriers, cirrhosis patients). Contrast-enhanced CT/MRI with LI-RADS scoring is the gold standard for non-invasive clinical diagnosis of HCC (no biopsy required for typical lesions). Liver biopsy is reserved for indeterminate lesions. Staging is primarily based on the BCLC (Barcelona Clinic Liver Cancer) system, with mandatory HBV/HCV viral load testing and Child-Pugh liver function assessment.

• Very Early/Early-Stage HCC (BCLC 0-A): Curative therapies are the standard of care, including surgical resection, liver transplantation, and thermal ablation (radiofrequency ablation [RFA] or microwave ablation [MWA]). These treatments achieve a 5-year OS rate of over 70%.
• Intermediate-Stage HCC (BCLC B): Transarterial chemoembolization (TACE) is the gold standard, with combination therapies (TACE + ablation, TACE + targeted therapy/immunotherapy) recommended for high-burden disease.
• Advanced-Stage HCC (BCLC C): Systemic therapy is the core of management. The first-line standard of care is immune checkpoint inhibitor combined with anti-angiogenic therapy. Multi-target TKIs are alternative first-line options. Locoregional therapies including TACE, HAIC, and radiotherapy are used as adjunctive treatment.
• Terminal-Stage HCC (BCLC D): Best supportive care, symptomatic management, and palliative interventions are the mainstay, with liver transplantation considered for strictly selected patients.