“No Radiation after a Mastectomy”… and other misconceptions

Mousey, what surgery have you had?  With such a small area of DCIS, and with it being low grade, your recurrence risk after a lumpectomy could be very low if good margins (10mm or greater) can be achieved.  This would be without Tamoxifen and radiation.  And even if the margins are smaller (let's say, 5mm in size) after Tamoxifen and radiation I would expect your recurrence risk to be well under 10%. 

Radiation cuts recurrence risk by approx. 50% and Tamoxifen can cut it by another 45%.  So to end up with a recurrence risk of 10% after both of these treatments, it would mean that your risk started out at around 35% after surgery.  That doesn't sound right - it's much too high a recurrence risk level for someone with a small low grade DCIS turmor.  Even to end up with a 5% recurrence risk after radiation and Tamoxifen means that you started out with a risk level of 18% after surgery - even that seems high.  I've seen studies that show that if good margins can be achieved, those who have <1cm low grade tumors have a recurrence risk in the range of 4% - 6% without any treatment post surgery.   </p>

So the key is the margin size.  With a tumor that is less than 1cm in size, in most cases good margins are possible.  And if you have good margins, you might not need radiation or Tamoxifen at all because your recurrence risk would already be very low.  Certainly these treatments would be optional.  Alternately, you could choose just to have radiation and forgo Tamoxifen, or vice versa. 

Is it possible to get a 2nd opinion?  Certainly you should do that if you are thinking about having a mastectomy in order to reduce your recurrence risk, but if a mastectomy is not really what you want to do.

I thought I would bump this post back up to the top of the current list because there are a number of newly diagnosed women on the board who have questions about DCIS.  There also has been quite a bit of incorrect information about DCIS floating around the discussion board. 

lago, I'm glad to hear that you are not going to need radiation.  I do need to clarify some of what you said, however, since this is the DCIS forum and most of the women reading this will be women diagnosed with DCIS.  Your situation is very different from theirs and from what you've explained, it sounds as though your benefit from rads will be lower, and your risks from rads will be higher, because of other treatments you are getting.

More specifically, your comment that your radiation oncologist "felt that all the added risk to my heart, lungs, bones etc. was not worth the reduced risk with rads" applies uniquely to your situation; it is not a general statement that applies to everyone.  In your situation, you are already getting chemo and Herceptin. Those treatments are given to reduce your risk of distant recurrence but they will also effectively lower your risk of local recurrence.  So adding radiation on top of this won't provide much incremental benefit.  Additionally, adding radiation on top of Herceptin, which already presents risks to the heart, might increase your risks even more.  This is why for you, the risks from radiation are not worth the reduced risk of recurrence that you'd get from radiation. 

I am concerned that someone with DCIS who has close margins after a mastectomy might read your statement and believe that the risks from rads are substantial and are greater than the benefit.  There are risks from rads but in fact the risks are low.  Of course, for those who have a low recurrence risk to begin with, it may be true that the benefit from rads might not be worth the risk.  However, for someone with DCIS who has close or positive margins, the potential benefit from rads (in terms of reducing recurrence risk) would be maximized because someone with DCIS may not be receiving any other treatments to reduce recurrence (specifically, chemo and Herceptin, which are not given to DCIS patients; Tamoxifen may or may not be given, depending on whether the cancer is ER+ or ER- and depending on whether the patient had a single vs. bilateral mastectomy).

I hope that this makes sense to anyone with DCIS.  This isn't to say that radiation is always necessary if you have close margins after a mastectomy, but each case needs to be evaluated individually and the risk/benefit equation of taking rads needs to be assessed based on the specifics of your diagnosis.   

These two studies explain the higher risk that some women with DCIS face after a mastectomy, and why in those cases, radiation might be recommended:

With a median follow-up of 61 months, 6 (7.5%) of the 80 patients developed local recurrence. Of the 31 patients with a margin of ≤2 mm, 5 (16%) developed local recurrence vs. only 1 (2%) of 49 patients with a margin of 2.1-10 mm (p = 0.0356)......Conclusion The findings of this review suggest that patients with pure ductal carcinoma in situ who undergo mastectomy with a margin of <2 mm have a greater-than-expected incidence of local recurrence. Patients with additional unfavorable features such as high-grade disease, comedonecrosis, and age <60 years are particularly at risk of local recurrence. These patients might benefit from postmastectomy radiotherapy.   http://www.redjournal.org/article/S0360-3016(08)03116-7/abstract

A total of 496 patients with pure DCIS were treated with mastectomy. None received any form of postmastectomy adjuvant treatment. Average follow-up was 83 months. Eleven patients developed recurrences, all of whom scored 10-12 using the USC/VNPI. No patient who scored 4-9 recurred. All 11 patients who recurred had multifocal disease and comedo-type necrosis. The probability of disease recurrence after mastectomy for patients scoring 10-12 was 9.6% at 12 years, compared with 0% for those scoring 4-9. There was no difference in overall survival.  Conclusions   There were no recurrences among mastectomy patients who scored 4-9 using the USC/VNPI. Patients scoring 10-12 were significantly more likely to develop recurrence after mastectomy. At risk were young patients with large, high-grade, and multifocal or multicentric tumors. For every 100 patients with USC/VNPI scores of 10-12, 10 patients will recur by 12 years and 2-3 will develop metastatic disease.  http://www.springerlink.com/content/d70rn4j73m950552/