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Medical Forum / Diseases and Disorders / Breast Cancer / June 2009Bone Scan vs. CT Scan; How to know for sure if it is metastatic disease?
Hello, My wife had breast cancer six years ago (diagnosed January 2003). She first had a lumpectomy. The sentinel node biopsy was negative. There was no sign of metastasis. The tumor itself was very prolific, though - Ki67 was 94%. Anyway, she then had a full course of chemo, and then started radiation. After she had already started radiation, she had genetic testing and discovered she was BRCA1 positive. Because of that, she stopped the radiation and opted for a double mastectomy (which took place about a year after finishing the chemo.) She has had no outward sign of cancer re-occurrence. However, about 1.5 years ago (a bit after our second son was born in 2007), she started having back pain / spasms. From the symptoms, it sounded like the description of a burst ovarian cyst. However, the doctors haven't found anything other than 'follicular cysts'. Anyway - that's a bit of an aside, but might be relevant. Last December (2008), she had an MRI of her spine. The report indicated an area that was likely due to arthritis (I forget the exact wording), and added that it was 'not likely due to metastatic disease'. Now a few weeks ago, she had a CT scan of her lower body. This scan showed areas of increased bone density in her pelvis and hip. (Note that she has not had any other scans in this area; no bone scans or anything else to compare with.) Because of that result, the doctor now wants to do a bone scan. *** Here is the crux of my post----> From what I understand, a bone scan only shows abnormal bone activity. How is this different than what the CT scan already shows? I've read that the test results are used in conjunction with medical history to determine if bone mets are the cause. So, do I already have the answer from the CT scan and medical history? Bone mets? Can they perform a biopsy, or some other more definitive test? My wife's mom (and grandmother) both have/had significant osteoarthritis (humped backs, etc.) So I'm certainly hoping that somehow the abnormal CT scan is related to arthritis. BUT HOW CAN WE KNOW FOR SURE? Sorry for the long post...but thank you for any help you can provide. Mike > Hello, > [quoted text clipped - 47 lines] > > Mike I am not a doctor but I've been around this loop with my late wife, some years ago. In short, it is not easy to tell. The longer answer is to observe progression. Cancer is distinctive by its invariant and geometric rate of progress regardless of anti-inflammatories, antibiotics etc. The isotope bone scan indicates areas of abnormal *activity*, ie inflammation, which can be cancer or arthritis etc.. The x-ray (including CT scan) indicates areas of abnormal bone *density*, so shows bone damage. The MRI images the density of water in the body, so in this situation is essentially a negative, precision x-ray, also giving better contrast between tumour and normal tissue. Cancers in bone may be lytic (bone eating) or blastic (bone building) or a combination of the two. Combining the bone scan image and a density image gives a pretty good confidence of what is and isn't cancer. Two sets of images at least 3 months apart make it pretty certain. A combination of a high isotope uptake, and visible distortions of the bone, especially with characteristic patterns, tend to indicate cancer. Bone mets are usually a diagnosis of last resort, the doctor will start off eliminating all other, more treatable conditions first, a) because they are treatable, and b) because mets are hard to detect. Yes you can do a bone biopsy, but you need at least an x-ray to identify the location to biopsy, plus you need a good reason to do it because it is an uncomfortable procedure. You can also do blood tests for various indicator compounds, but these tend to lag behind the cancer, and have a very variable base level, so are not very useful at this stage. In all these test you, or your medical professionals, have to be thinking about what difference the result of he test will make to the treatment. It's always nice to "know what is going on" but sometimes it can be more trouble/pain/cost than it is worth, when the result of the test will have little effect on treatment or outcome. Tim Jackson >> ....Now a few weeks ago, she had a CT scan of her lower body. This scan >> showed areas of increased bone density in her pelvis and hip. (Note >> that she has not had any other scans in this area; no bone scans or >> anything else to compare with.).... > ....The x-ray (including CT scan) indicates areas of abnormal bone > *density*, so shows bone damage. .... Cancers in bone may be lytic (bone > eating) or blastic (bone building) or a combination of the two..... ------------------ Couldn't the increased bone density be due to Paget's disease too? Eva >>> ....Now a few weeks ago, she had a CT scan of her lower body. This scan >>> showed areas of increased bone density in her pelvis and hip. (Note [quoted text clipped - 8 lines] > > Eva Oh yes, lots of causes, could be dietary factors too, that's why you need both pieces of information, plus an expert eye to recognise the typical formations. I suppose if Paget's were a consideration you might end up doing a bone biopsy. Tim > Last December (2008), she had an MRI of her spine. The report > indicated an area that was likely due to arthritis (I forget the exact [quoted text clipped - 24 lines] > somehow the abnormal CT scan is related to arthritis. BUT HOW CAN WE > KNOW FOR SURE? Biopsy is the only way of knowing 'for sure'. As Tim pointed out it can be uncomfortable and one has to weigh the pros and cons beforehand. A bone scan is good, but an MRI of the pelvis would also provide additional info. I find it very sensitive to various bone conditions but CTs are quicker to read. They could also check her tumor markers (CEA and CA15-3 or whatever your region offers for breast ca) with a blood test. By putting all the bits of the puzzle together one can make an accurate assessment of what the lesions are, without a biopsy.  Signaturemadiba They could also check her tumor markers (CEA > and CA15-3 or whatever your region offers for breast ca) with a blood > test. By putting all the bits of the puzzle together one can make an > accurate assessment of what the lesions are, without a biopsy. How reliable are these blood tests? Last month I registered 44 on the CA 27-29 and was told anything above 40 was abnormal. I requested confirmation of the result and took another test two weeks later - the CA 27-29 and the CEA (at another lab). This time both results were normal (35 on the CA 27-29). That seems a huge variation in such a short time. I'm inclined to forego these tests in the future since they are so anxiety producing and may be unreliable. MMH > They could also check her tumor markers (CEA > > and CA15-3 or whatever your region offers for breast ca) with a blood [quoted text clipped - 8 lines] > time. I'm inclined to forego these tests in the future since they are > so anxiety producing and may be unreliable. Tumor markers can be extremely sensitive -PSA is an example where shifts of 0.01 increments can be significant, when there is a definite trend to be seen eg 3 consecutive low results, but each one higher than the previous one. Similar situation with breast markers, do several at 1 to 3 monthly intervals and determine the trend. With breast markers there is more variation than with PSA but with time you should see the trend. The problem is breast ca is usually more urgent. Perhaps the numbers in your case continue to fall (for whatever reason) which is good news. Absolute reliance on any of these parameters is not good, even biopsies sometimes. The main problem with breast markers is false negative results. Signaturemadiba |
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