Friday, May 23, 2014


    The doubling  time is a term I have used . I do know that the many lawyers like to use this in suing doctors . But what I am talking about is the use of doubling time in following the abnormal CT scans.In past we really did not have much idea as to the growth pattern of the cancers . But as we have followed more and more patients and are doing more CT scans , we now have some way of estimating the growth patter of the cancer. The interesting part is that the same tumor may not have same rate of growth at the same site or at other site , the metastatic tumor .So we have no 100 % test to know.To understand the doubling time we must first understand the origin of cancer.The body has great mechanism and it does not allow the growth of cells when it is not needed.So if I have a cut in my skin , the cell will start growing and as soon as the gap is filled then the growth will stop . This happens automatically.When the cell continues to grow and there is no control on the multiplication of the cells , then it is cancer. This is very simple explaination, and not the perfect one . But this comes as close to the real one.So if we believe that the cancer starts in one cell getting out of control. and continues to grow and DOUBLES , then again multiplies ,and becomes 4 , and then 8 and so on .So when we talk about the doubling time , we are not talking about time taken to double , but the time taken to double volume ,is called doubling time .So we are not talking about 1cms becoming 2cms , but the volume becoming double . The lung cancers have widely variable doubling time.It may be as fast as 45 days to as slow as 400 days.This means that the tumor may double in month and a half or year and the half . So this does not help much . But then majority of cancers will double in 3 to 4 months.So that is where we have some recommendations as to doing the follow up CT scans . But the case that I am going to tell is one which lies outside these patterns.
       I can remember many cases but I am going to tell about some . I was following this. semiretired nurse for shortness of the breath . She had history of breast cancer and it was operated and she was fine . But then was short of breath.The further work up revealed that she had developed inflammation and asthmatic reaction . On further work revealed that she was allergic to hays that is fed to the horses , and it was causing the inflammation and the scar tissues . I told her to stop taking care of the horses and she improved . So I was doing follow up on CT scans and breathing tests.She did well for next 3 or 4 years . So I was then doing yearly X-ray , rather than CT scan. One year I did the chest X-ray and it showed 9 cms size lung mass. She had no symptoms . So when I told her about it ,she thought it may be the breast implant leaking .We did the CT scan and it confirmed the lung mass and then the biopsy confirmed the lung cancer . So this cancer must have had very rapid growth patter as otherwise it could not have grown to this size so quickly.
       The other case that I will tell in future is one where a plain X-ray was reported normal , and the patient had wide spread cancer in less than 3 months . In one other case there was a spread of lung cancer ,that we could not find out in spite of CT scan of the lung.So the doubling time good for many patients or may be most patients , but is not 100%.  

No comments:

Post a Comment