By: NAPOLEON Y. DE GUZMAN, MD, FPCS, FPATACSI
Bronchogenic Cancer or Lung Cancer is the most common cancer in men, and the 3rd most common in women.[i]
It is generally classified into two types: small cell lung cancer (SCLC), and the non-small cell lung cancer (NSCLC).
The small cell variety, sometimes called oat cell lung cancer, is very aggressive with poor prognosis. It is not uncommon to find 10% of patients with brain metastases[ii] upon diagnosis. The lesions are usually beyond surgical resection because of early spread. They are initially responsive to chemotherapy and radiotherapy. The tumor may present as a solitary pulmonary nodule, in which case it is classified as “limited disease”.[iii]
The non-small cell variety are amenable for surgery.[iv],[v] They are classified into: squamous, adenocarcinoma, and large-cell types. Presently, the most common is adenocarcinoma, which is a common cancer for both smokers as well as non smokers. Previously, the most common was squamous cell carcinoma – the type associated with smoking. The large-cell type is an undifferentiated cancer, like the small-cell type. But unlike the small-cell type, surgery is still recommended, if the lesion is resectable.
Chest X-Ray is the screening procedure of choice but CT scan is emerging as the preferred choice since it can detect small lesions.[vi] Histopathology of the lesion is needed for the diagnosis. Fiber-optic bronchoscopy is the diagnostic procedure of choice for central lesions. Samples from bronchial brush and washings can yield positive results. A punch biopsy can likewise be done when endobronchial lesion is seen. Transbronchial needle biopsy is an available option. Percutaneous transthoracic needle biopsy is used for peripheral lesions. This is done with imaging devices like CT scan or thoracic ultrasound. The biopsy under ultrasound makes use of real time imaging.
Sometimes needle biopsies of pulmonary mass may yield indeterminate results. Up to 3 needle biopsies can be done, beyond which, an open biopsy is the preferred procedure for diagnosis. In solitary pulmonary nodules, if the probability of malignancy is high (by Baye’s theorem[vii]), a wedge resection with frozen section may be done via video-assisted thoracic surgery (VATS), or a limited thoracotomy. The solitary pulmonary nodule is of interest to the pulmonologist because, if malignant, it is an early stage lung cancer, amenable to resection and with a high 5-year survival. A histologic diagnosis must be made within one (1) month’s time so that resection by VATS or open thoracotomy can be done.
In lung cancer, after a histologic confirmation is made, staging is done either by CT Scan or by mediastinoscopy/mediastinostomy. The advantage of CT scan is that it is non invasive. The disadvantage is that, there is no histologic confirmation of the nodes. However, nodes can be examined during surgery and staging determined. Positron emission tomography (PET) is helpful in preoperative staging but its high cost is a limiting factor.
Staging is necessary in planning treatment for the non-small cell variety.[viii] Surgery is the primary treatment for TNM Stages 1 and 2. Stage 3a needs a neoadjuvant treatment before surgery. The advantages of neoadjuvant treatment are: the tumor may shrink, and one can determine if the tumor is sensitive to chemotherapy. Palliative and supportive treatment is recommended for Stages 3b and 4, taking into consideration the patient’s performance status.
Though the overall 5-year survival is not good, the advances in treatment (oncology, immunotherapy, targeted therapy) are giving fresh outlook for patients with lung cancer. The advances in anesthesia have made surgery for lung cancer safer. The advent of minimally invasive procedure (Video Assisted Thoracic Surgical resection) has become the preferred option because of its advantages in terms of less pain, short hospital stay, small incision but most of all, the early return to pre operative status.[ix],[x]
[i] Gloor, R. (June 5, 2017). Lung Cancer. Retrieved June 8, 2017 from http://www.pchrd.dost.gov.ph/index.php/news/library-health-news/3540-lung-cancer
[ii] Quan, A.L, Videtic, G.M.M., & Suh, J.H. (July 1, 2004). Brain metastases in small cell lung cancer. Retrieved June 8, 2017 from http://www.cancernetwork.com/oncology-journal/brain-metastases-small-cell-lung-cancer
[iii] American Cancer Society. (March 2, 2017). Small cell lung cancer stages. Retrieved June 8, 2017 from https://www.cancer.org/cancer/small-cell-lung-cancer/detection-diagnosis-staging/staging.html
[iv] National Cancer Institute. (March 31, 2017). Non-small cell lung cancer treatment. Retrieved June 8, 2017 from https://www.cancer.gov/types/lung/hp/non-small-cell-lung-treatment-pdq#section/_514
[v] National Comprehensive Cancer Network. (2017). NCCN Guidelines Version 6 Non Small Cell Lung Cancer NCCN Blocks. Retrieved June 8, 2017 from https://www.nccn.org/professionals/physician_gls/pdf/nscl_blocks.pdf (Log-in required)
[vi] Detterbeck, F.C., Mazzone, P.J., Naidich, D.P., & Bach, P.B. (May 2013). Screening for Lung Cancer. Diagnosis and Management of Lung Cancer, 3rd ed – American College of Chest Physicians Evidence-Based Clinical Practice Guidelines. Retrieved June 8, 2017 from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3749713/
[vii] Gould, M.K., Ananth, L., & Barnett, P.G. (February 2007). A clinical model to estimate the pretest probability of lung cancer in patients with solid pulmonary nodules. Chest Vol. 131(2), pp. 383-388. Retrieved June 8, 2017 from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3008547/
[viii] NCCN (2017). NCCN Guidelines Version 6 Non Small Cell Lung Cancer NCCN Blocks. Retrieved June 8, 2017 from https://www.nccn.org/professionals/physician_gls/pdf/nscl_blocks.pdf (Log-in required)
[ix] Enewold, L., Mechanic, L.E., Bowman, E.D., Zheng, Y.L., Yu, Z., Trivers, G., Alberg, A.J., & Harris, C.C. (January 2009). Serum concentrations of cytokines and lung cancer survival in African Americans and Caucasians. Cancer Epidemiology Biomarkers Preview Vol. 18(1), pp. 215-222. Retrieved June 8, 2017 from https://www.ncbi.nlm.nih.gov/pubmed/19124500
[x] Walker, W.S., & Leaver, H.A. (May 2007). Immunologic and stress responses following video-assisted thoracic surgery and open pulmonary lobectomy in early stage lung cancer. Thoracic Surgery Clinics Vol. 17(2), pp. 241-249. Retrieved June 8, 2017 from http://www.sciencedirect.com/science/article/pii/S1547412707000308
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