Confused about DCIS Pathology and Next Steps

BCAE

I had my lumpectomy 2 weeks ago. My originally core needle biopsy showed only 6mm of tumor. However I talked with my surgeon about the lumpectomy pathology report and now my tumor size is much larger but I am really unclear as to exactly how big. My BS says the reason for the vagueness is that she took out a main section of tissue and then she went back to take out 2 more parts. In the report it refers to the first part to be "estimated within 1cm and the larger size in one section is 0.5cm," and then another 2nd part "at least 2cm". The 3rd part had no DCIS. For the summary, overall tumor size is "at least 2cm." My BS says that because you need to somehow combine the first part to the second part to estimate the tumor size, it's "at least 2cm." So she thinks it to be between 2-3cm. She says this pathologist is a breast cancer expert and is "rarely wrong", and doesn't think I need a second opinion. (And I'm not entirely sure I have time at this point, because I am wanting to do APBI.) But it is frustrating to me that everything is so vague. (I even thought about calling the phone number pathology report just to talk to the pathologist myself...but I read that that is not really proper protocol!) The main problem for me is that I had the Oncotype DCIS test done (I am low risk - 10% recurrence, 4% invasive recurrence), but I know with that test my tumor needs to be 2.5cm and under. My BS said that the Oncotype results may be unreliable given that my tumor size *could* be bigger. I was hoping to rely on the Oncotype for clarity for my decision about radiation and tamoxifen, but now I am so confused! I've read about Esserman's work and if my tumor size had stayed the same, I would have not done radiation...now I don't know! Any advice?

brigid_TO

Hi BCAE

I don't believe that is correct -that your tumour has to be 2.5 cm or less in order to have a reliable Oncotype DCIS test. That may have been the parametres of the original studies but not now.

The radiation decision is tricky but I will speak as someone who went through 21 zaps (16 plus 5 boosts) Whole Breast Radiation-Hypofractionated it is doable. My only real side effect to date is some minor tightness in my arm that I am working on. My circumstances were a bit different. I had one close margin 1mm and later came to find a spot of microinvasion less than 1mm. Getting the pathology right is important to decision making- a 2nd opinion might help- some labs can do it quite quickly.

I started and stopped Tamoxifen- still trying to figure that one out. My main focus now is on diet, exercise and the extra things that can be done to reduce recurrence or new primary.

MinusTwo

You didn't say if you are HER2 positive. I know they don't usually test for DCIS, but in your case you might push it. I sure wish I had, since I ended up with a recurrence that turned into IDC within 2 years. Otherwise I'd probably at least do the rads.

BCAE

Actually the 2.5 cm or less of tumor is what is printed on the actual Oncotype test result. These are the people they have based the percentages on. Have you read something different?

They did not test for Her2 (I do have necrosis present though), and haven't read that much about using that in understanding DCIS. Can you tell me what difference it would make in how I understand my risk of recurrence?

Beesie

Based on the current research and understanding of DCIS, HER2 status would not make any difference in recurrence risk. Nor are there any differences in treatment for those who have HER2+ DCIS vs. those who have HER2- DCIS. This is why HER2 status is not usually tested when the diagnosis is pure DCIS.

HER2+ invasive cancer is known to be extremely aggressive but the research to date on DCIS does not support this same conclusion. In fact the most recent research on this came to the opposite conclusion, that HER2+ DCIS might be less likely to develop into invasive cancer. That's just one study, however, so no one is taking that to the bank. But quite a few studies have looked into this, and most show no greater aggressiveness for HER2+ DCIS.

https://bmccancer.biomedcentral.com/articles/10.11...

What is known for sure is that approx. 40% of DCIS cases are HER2+, whereas only about 20% of invasive cancer diagnoses are HER2+. No one understands why this is but it certainly seems contrary to the concern that HER2+ DCIS may be more likely to develop into invasive cancer.