Overview
Definition:
S7+8 basilar segmentectomy is a precise surgical procedure involving the removal of lung segments 7 and 8, which together form the posterior basal segment and lateral basal segment of the lower lobe, respectively
This technique is employed in the management of peripheral lung malignancies or other focal lung pathologies located within these specific segments, aiming for oncologic control with lung parenchyma preservation.
Epidemiology:
Lung cancer remains a leading cause of cancer-related deaths globally and in India
While lobectomy is the standard for early-stage non-small cell lung cancer (NSCLC), segmentectomy is increasingly utilized for small, peripheral tumors, particularly in patients with compromised pulmonary function
Specific data on the incidence of tumors necessitating S7+8 segmentectomy is limited, but it represents a subset of cases where limited resection is oncologically sound and functionally beneficial.
Clinical Significance:
This procedure is crucial for optimizing oncologic outcomes while minimizing lung volume loss
For patients with limited pulmonary reserve, preserving lung function through segmentectomy rather than a full lobectomy can significantly improve postoperative quality of life and reduce morbidity
It allows for precise tumor removal while maintaining adequate respiratory capacity, a critical consideration for long-term patient survival and well-being.
Indications
Oncologic Indications:
Primary early-stage NSCLC (T1a or T1b, N0 M0) with a tumor size typically ≤2 cm, located in segments S7 or S8
Tumors with clear margins after resection and no lymphovascular invasion
Recurrent or metastatic lesions amenable to resection within these segments.
Non Oncologic Indications:
Benign lung tumors or nodules in segments S7/S8 that are symptomatic or suspicious for malignancy
Recurrent infections or bronchiectasis localized to these segments that are refractory to medical management
Pulmonary arteriovenous malformations (AVMs) or other vascular lesions in the S7/S8 distribution.
Functional Considerations:
Patients with marginal pulmonary function (e.g., severe COPD, reduced FEV1) where a lobectomy would lead to significant respiratory compromise
Selection is guided by thorough pulmonary function testing (PFTs), CT volumetry, and cardiopulmonary exercise testing (CPET).
Preoperative Preparation
Diagnostic Workup:
Comprehensive evaluation including chest X-ray, contrast-enhanced CT scan of the thorax for tumor staging and vascular anatomy, PET-CT for distant metastasis assessment, and potentially bronchoscopy with biopsy
Pulmonary function tests (PFTs) are essential.
Patient Counseling:
Detailed discussion with the patient and family about the procedure, potential risks and benefits, alternative treatments (e.g., stereotactic body radiation therapy - SBRT), and the possibility of conversion to lobectomy if oncologic margins cannot be achieved with segmentectomy.
Medical Optimization:
Smoking cessation programs, optimizing respiratory physiotherapy, and management of comorbidities such as COPD, hypertension, and diabetes
Nutritional assessment and supplementation if needed.
Procedure Steps
Surgical Approach:
Performed either via video-assisted thoracoscopic surgery (VATS) or thoracotomy
VATS is preferred for minimally invasive access, leading to faster recovery and reduced pain.
Segmental Dissection:
Careful identification of segmental bronchi and pulmonary vessels supplying segments S7 and S8 using preoperative imaging and intraoperative visualization
The intersegmental veins are identified and ligated
The segmental bronchus (for S7 and S8, originating from the superior division of the lower lobe bronchus) is dissected and divided
The segmental artery and vein are isolated and ligated.
Parenchymal Transection:
The lung parenchyma is transected along the fissureless plane or using an energy device (e.g., stapler) to achieve clear margins around the tumor
Hemostasis and air leak assessment are critical.
Lymphadenectomy:
Systematic mediastinal lymph node dissection (station 2R, 4R, 7, 8, 9 for right side
2L, 4L, 7, 8, 9 for left side) is performed for oncologic staging and clearance
Sampling of interlobar nodes (station 10) and hilar nodes (station 11) is also standard.
Postoperative Care
Pain Management:
Multimodal analgesia including epidural anesthesia, patient-controlled analgesia (PCA), and oral analgesics
Early mobilization is encouraged.
Respiratory Support:
Chest tube management for pleural drainage
Incentive spirometry and chest physiotherapy to prevent atelectasis and pneumonia
Monitoring of oxygen saturation and respiratory rate.
Monitoring:
Close monitoring of vital signs, fluid balance, and urine output
Assessment for complications such as pneumothorax, hemothorax, chylothorax, air leak, and infection
Serial chest X-rays to assess lung expansion and detect complications.
Complications
Early Complications:
Persistent air leak (>5 days)
Pneumonia
Hemorrhage or hemothorax
Chylothorax
Bronchopleural fistula
Atelectasis
Atrial fibrillation.
Late Complications:
Chronic air leak
Post-thoracotomy pain syndrome
Diaphragmatic dysfunction
Recurrence of malignancy
Development of new primary lung cancer.
Prevention Strategies:
Meticulous surgical technique, adequate stapler usage for bronchial and vascular division, secure pleural closure, and appropriate chest tube management
Prophylactic antibiotics and early ambulation
Comprehensive preoperative assessment to identify high-risk patients.
Prognosis
Factors Affecting Prognosis:
Histological subtype of lung cancer, tumor stage (including nodal status and margins of resection), patient’s overall health status, and adherence to postoperative care and surveillance
Completeness of lymphadenectomy is also crucial.
Outcomes:
For early-stage NSCLC, segmentectomy offers comparable oncologic outcomes to lobectomy when performed for appropriate indications
The main advantage is preserved lung function, leading to better long-term quality of life
Survival rates are generally high for stage I disease, with 5-year survival rates often exceeding 70-80% for well-selected patients.
Follow Up:
Regular follow-up appointments with chest imaging (CT scans) every 3-6 months for the first 2-3 years, then annually, to monitor for recurrence or new primary lung tumors
Continued pulmonary rehabilitation and smoking cessation support.
Key Points
Exam Focus:
Understand the segmental anatomy of the lung, especially the S7 and S8 segments
Recognize indications for segmentectomy versus lobectomy in early-stage lung cancer
Key elements of preoperative assessment and postoperative management
Complications specific to segmentectomy and their management.
Clinical Pearls:
VATS approach offers superior outcomes for most segmentectomies
Intraoperative identification of intersegmental veins is critical for preventing congestion of the remaining segments
Complete mediastinal lymphadenectomy is essential even for small peripheral tumors to ensure accurate staging
Always assess for air leaks and perform thorough hemostasis.
Common Mistakes:
Inadequate margin of resection
Incomplete lymphadenectomy
Failure to identify and ligate segmental vessels and bronchi precisely
Performing segmentectomy for tumors with unfavorable features (e.g., central location, lymphovascular invasion)
Underestimating postoperative respiratory complications in patients with pre-existing lung disease.