LUNG CANCER PART-3
(All the articles published in past are available at www.shyamhemoncclinic.com/blog/)
Question: Thank you Chiragbhai for explaining about why late diagnosis is common in India, and how to make early diagnosis. It is time our colleagues realize that tuberculosis is less common now, and lung cancer is increasingly more common. Hence empiric tuberculosis treatment should no longer be considered appropriate in most cases. Not just this, similar lung finding may be found in fungal or other uncommon infections as well. Recently we found plenty of Strongyloides in bronchoscopy (BAL specimen), in a patient with high suspicion of tuberculosis by radiological findings.
You have nicely covered cancer prevention and early diagnosis in your book also, titled “Cancer Can Be Cured” or in Gujarati “Cancer Mati Shake Che”. Last time, you had started talking about role of PET-CT in staging, and MRI. Can you tell us more about that?
Ans: Yes. Before starting treatment, we need to know type of tumor, stage, and molecular characteristics of the tumor. Small cell OR Non small cell are the two broad categories in tumor type. Accurate staging is also important, as the treatment is very different stage wise. Minimum required tests are CT scan of chest and upper abdomen including adrenal glands. Bone scan is added if symptoms suggestive of bone involvement or raised alkaline phosphatase. In some patients, accurate staging can be quite difficult, due to suspicious mediastinal node involvement, or small pleural effusion or pleural nodule, or occasional spot in bone, or additional lung nodule (apart from primary tumor) or a small lesion in brain or in liver or in adrenal gland. These are important points as stage may change from early to advance, hence treatment may change, for example from surgery to only palliative chemotherapy. Most of these sites require biopsy confirmation preferably or some additional test to determine stage accurately. If there are multiple metastatic sites, additional biopsy is not required.
PET-CT scan (combined PET and CT scan. Most new machines are now combined. Earlier machines used to be only PET where correlation of hot spot on PET and actual site in body were sometimes difficult) is a very useful advance test which helps in more accurate staging of lung cancer, and many other cancers. It covers essentially whole body. It is not very accurate for detecting small metastases in brain, hence if patient has stage 2 or 3 lung cancer, additional brain MRI should be considered to ensure right stage.
Non small cell lung cancer can have metastatic disease at almost any site in the body, even at presentation, hence a whole body scan like PET-CT is very useful. Wherever available, it should be done as the initial test. However if patient already comes with a CT scan (and/or sonography, bone scan etc) and has obvious metastatic disease, further PET-CT is not required to identify all sites of metastatic disease. Main importance of initial work up is in ensuring proper staging between stages 1 to 3 and stage 4, as the treatment is very different for these two subgroups. Finer details of stage, between 1 to 3, are beyond the scope of our discussion, but in short it involves multidisciplinary evaluation and occasionally advance tests such as mediastinoscopy etc.
Que: Oh! I thought determination of stage would be a very simple thing, and ordering a scan would be all that we need. Before we go to treatment, don’t we have a screening test like we do for breast cancer, for such a deadly and common cancer?
Ans: Yes, staging a lung cancer accurately is sometimes a very difficult issue.
For early diagnosis of lung cancer, tests like chest x ray, sputum cytology, routine CT scan etc have not been cost effective or safe enough. Recently, a special LDCT (low dose CT scan) has been approved for screening in patients at risk, such as those with history of heavy smoking. The NLST (national lung screening trial) which showed this positive finding, had shown improvement in both lung cancer specific as well as overall survival. In this study of over 53,000 patients, who had annual low dose CT for 3 years, showed 20% reduction in lung cancer related deaths. Most major professional organizations in USA, Canada, and Europe now recommend LDCT for lung cancer screening.
Such scans use one third dose of radiation, are done without contrast, and should be repeated every year, in patients who are current or former heavy smokers (over 30 pack years), and age over 55. Different guidelines recommend different duration, from 3 consecutive years total, or up to age 80. One must remember that this is the only study to show benefit, and there is a risk of false positives requiring unnecessary biopsies, occasionally even surgery, complications, anxiety, and cost.
Hence this cannot be recommended for widespread use in India, but may be useful for few selected motivated people and where facilities for such scans and proper reading exist.
May 15th 2016.
Dr. Chirag A. Shah; M.D. Oncology/Hematology (USA), 079 26754001. Diplomate American Board of Oncology and Hematology. Ahmedabad. firstname.lastname@example.org Shyam Hem-Onc Clinic. 402 Galaxy, Near Shivranjani, Opp Jhansi ki Rani BRTS, Ahmedabad. www.shyamhemoncclinic.com