In medicine we observe and then do investigation and then come to conclusion on certain FACTS. We recently started doin Low Dose Radiation CT scan of chest to diagnose lung cancer in early stage. The test was approved for patients who have been smoker or ex smoker for 14 years and over certain age and certain pack year history. This has created sometimes more problem than answer. We have seen tiny nodules - mm in size that we do know what to do. Then we came with some suggestion to do follow up on theses nodules. At mm size we cannot get the tissue with needle biopsy and with PET SCAN and we cannot operate on everyone. So we have developed some criteria as to how often to do follow up on these nodules with CT scan. If the nodule is 8 mm -1/3 rd of inch then we need to do follow up in 3 months , if it is 5-8 mm then do CT scan in 4 months and if less than 5 mm then do CT scan in 66 months. This is based on what is called Doubling Time.-How much time a cancer will take to double in VOLUME. Again not all cancers double in same time and there are outliers. So some will be very slow growing and some will be fast growing . That brings me to my patient for today.
This patient was followed by me for some years . He had been smoker in past and had COPD . He had CT scan and had 4 mm nodule. We had done some follow up CT scan and the nodule had not changed for more than 1 year. The average doubling time of lung cancer is 90 to 10 days and so we usually do CT scan follow up in 3-4 months. Again not all will follow this growth pattern and sometimes same cancer may have different growth rate at different time and in different organs when it metastasizes. But it is good way to do the follow up . So he was stable . Roughly about 9 months after his last CT scan chest ,he saw cardiologist . He decided to do CT scan to check on his aorta.. That showed stable 4 mm nodule but showed NEW MASS of 2.5 cm or one inch. I saw him and did the work up . He had PET SCAN and that showed increased uptake. There is some size difference between the PET scan and CT scan . But the point that I am trying to make is how did this inch size tumor happened when there was none 8 months ago. What is the growth pattern and why on PET scan it is not same rate increasing but some decrease in size. But in general the doubling time is good way to do follow up . But not all CANCERS HAVE HEARD ON THIS OR DON'T WANT TO FOLLOW TH RULES !!!
