LUNG CANCER PART-4
(All the articles published in past are available at www.shyamhemoncclinic.com/blog/)
Question: Thank you Chiragbhai for explaining role of various tests in staging, especially the fact that PET-CT scan should be used now in almost all patients who don’t have obvious stage 4 disease at presentation. PET-CT is much more accurate compared to CT scan in staging lung cancer. It’s use will prevent many unnecessary surgery or radiotherapy.
Screening of high risk individuals for early detection of lung cancer, using a special LDCT (low dose CT scan) was a completely new knowledge for me. I am glad it is available in our region also. Hopefully our readers will consider recommending this to some of their patients who are heavy smokers. Before we proceed to treatment, can you clarify something about predictive tests you had mentioned earlier? We have heard of prognostic tests, but what is a predictive test?
Ans: Most predictive tests are a very new thing in oncology. Prognostic tests tell us how bad the tumor is, in short. Predictive tests, on the other hand, tell us whether a particular treatment is more or less likely to work. For example, EGFR mutation predicts higher chances of responding to anti EGFR therapy such as oral tyrosine kinase inhibitor Gefitinib. Or ALK mutation predicts higher chances of responding to anti ALK therapy such as oral tyrosine kinase inhibitor Crizotinib. (a similar very old example is in breast cancer, where a positive estrogen receptor test predicts response to hormone therapy).
These tests are not 100% however. A positive test is not a guarantee that a targeted therapy will definitely work, and vice versa.
Que: That is amazing. This is like culture sensitivity testing for antibiotics – whether a particular antibiotic is likely to work or not. Now, let us discuss treatment options, starting with early stages.
Ans: Early stages include 1, 2 (stage 1, 2 is without mediastinal involvement. Some patients are upstaged at surgery, when mediastinal involvement is found). In short:
• Stages 1, 2 are treated by surgery.
• Surgery is either lobectomy or pneumonectomy (removing whole lung on one side). Less than lobectomy (segmentectomy, wedge resection) is rarely done, for very small tumors only, as there is higher risk of relapse otherwise.
Other important points for STAGES 1 and 2:
1. Stage 1A – only surgery.
2. Stage 1B (large over 4 cm), 2A, 2B – postoperative chemotherapy is indicated. It has shown absolute survival improvement in the range of 4-15% in different studies. (remember that most postoperative treatments in oncology improve absolute survival in the range of 5%. To compare, emergency angioplasty in acute myocardial infarction improves survival by 4-6% only, and streptokinase by 2% only). Most of the positive studies used cisplatin vinorelbine or cisplatin etoposide. In clinical practice, carboplatin is frequently used due to poor tolerance of cisplatin.
3. Postoperative Radiotherapy is not standard of care. It may be indicated in patients with positive margins after surgery, but not routinely. In fact, some studies have shown increased mortality with routine use after surgery.
4. Targeted therapies like gefitinib erlotinib etc are not indicated in this setting.
5. Preoperative chemotherapy is not indicated in this setting.
6. Fitness for surgery (ability to tolerate lobectomy or pneumonectomy) is determined by various tests, such as PFT (pulmonary function test), DLCO (diffusion capacity), oxygen consumption test, ability to climb one flight of stairs without stopping, etc. most commonly used measure is FVC (forced vital capacity) which should be more than 1 Litre predicted postoperatively. Otherwise there is a high risk that patient would have serious morbidity after surgery, such as extremely reduced functional capacity or unable to come off ventilator or mortality. Lung function should be maximized preoperatively by use of bronchodilators, treatment of infection, lung exercises like incentive spirometry, weight reduction in obese patients, quit smoking etc.
7. For patients who remain unfit for surgery, or not willing, there are small studies to show that standard radiotherapy may cure up to 15-35% of patients. Newer methods like SBRT (stereotactic body radiotherapy) which gives high doses to small volume areas, have shown 80% survival at two years. SBRT is useful however only for smaller tumors, preferably below 4-5 cm. These new techniques are also available in our region.
June 5th 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