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Jan 21, 2009 12:44PM, edited Jan 21, 2009 02:06PM
If your specialist said that there is only a 10% - 30% chance that your DCIS will develop into invasive cancer, he was referring specifically to your situation. You say that you were diagnosed with low grade DCIS - I assume grade 1? And how much DCIS did you have? If you had only a small amount of low grade DCIS, there is evidence to suggest that the risk that it might become invasive is probably quite low, but the statement your doctor made most certainly does not apply to all cases of DCIS and anyone else who is newly diagnosed should not assume that what he said applies to them. To my earlier post, all cases of DCIS are not created equal.
The fact is that while it's currently believed that not all DCIS will go on to become invasive cancer, the % that will become invasive is unknown - I have seen some estimates as low as 25% but most sources estimate that approx. 50% of DCIS will become invasive and I've seen some estimates that are higher than that. The most well-respected breast cancer authorities simply don't venture a guess because they know that there is no good information on this. For example:
Because of increased screening with mammograms, the rate at which DCIS is diagnosed has increased dramatically in recent years. Fortunately, the condition isn't life-threatening, but it does require treatment. Unlike lobular carcinoma in situ (LCIS) - which really isn't a cancer at all but a marker for increased risk of developing invasive breast cancer - DCIS is more likely to develop into invasive breast cancer if left untreated. Http://www.mayoclinic.com/health/dcis/DS00983
Ductal carcinoma in situ (DCIS) is a noninvasive condition. DCIS can progress to become invasive cancer, but estimates of the likelihood of this vary widely. http://www.cancer.gov/cancertopics/pdq/treatment/breast/HealthProfessional/page5 While virtually all invasive cancer begins as DCIS, not all DCIS will go on to become an invasive cancer. An invasive cancer is one that has the potential to metastasize (spread). Right now we have no way to determine which DCIS will go on to become invasive cancer and which will not. That's why doctors recommend DCIS be treated.
Http://www.dslrf.org/breastcancer/content.asp?L2=3&L3=2&SID=164Having DCIS means that a woman has an increased risk for developing invasive breast cancer in the future, unless she has treatment. With appropriate treatment, DCIS is unlikely to develop into invasive cancer. A woman with DCIS does not need all the same treatment as a woman diagnosed with invasive breast cancer, but she does need surgery to remove the DCIS, and radiation to ensure that any stray, abnormal cells are destroyed. This lowers the risk that the DCIS will recur or that invasive breast cancer will develop.
Overall, it's estimated that about 20 to 30 percent of women with untreated, low grade DCIS go on to develop invasive cancer. It's not currently known how common it is for higher grade DCIS to turn into invasive disease. Http://ww5.komen.org/BreastCancer/DuctalCarcinomainSitu.html
This particular topic - the % of DCIS that becomes invasive - comes up frequently on this discussion board and it happens to be one of my hot buttons (but then you may have already guessed this). Rather than repost everything that's been posted on this before, here is a link to a thread from last year where most of the current science on this was presented:
Edited to add: musicale257, I just reread this post and it reads a bit like I'm jumping on you. I apologize for that; it wasn't my intent at all. While personally I believe that all DCIS should be removed, I also agree with you that there is a lot of overtreatment of DCIS. That's why I always emphasize the point that not all cases of DCIS are the same. The risk of recurrence and the risk of invasion for someone who has a small low grade DCIS is very different than these same risks for someone who has a large area of aggressive DCIS. And because of that, the treatment considerations can be quite different too. In my time on this board, too often I've seen women gravitate towards treatment advice from others who've had a very different diagnosis. This can lead to undertreatment or overtreatment. For example, my decision to have a mastectomy because I had 9 cm of high grade DCIS (along with a microinvasion of IDC) offers no guidance whatsoever to someone who's been diagnosed with <1cm of low grade DCIS. Similarly, your decision to opt out of treatment after being diagnosed with low grade DCIS should not be taken as a reassurance that no treatment is necessary for someone diagnosed with high grade DCIS. It would be nice if doctors explained DCIS better so that we each understood where we stand in the DCIS spectrum, but unfortunately most of us come here with little understanding of DCIS and how variable it can be.
Dx 9/15/05, DCIS-MI, 6cm+ Gr3 DCIS w/IDC microinvasion, Stage I, 0/3 nodes, ER+/PR- “No power so effectually robs the mind of all its powers of acting and reasoning as fear.” Edmund Burke