Wednesday, January 16, 2008

Would you want to know? Testing your children for the breast cancer gene (BRCA)


*At right is a computer model of the BRCA-1 gene protein

The American Journal of Medical Genetics published a provocative paper this month titled, "Should genetic testing for BRCA1/2 be permitted for minors?" and reflected the surveyed opinions of adult carriers of the most defined "breast cancer gene" mutations, BRCA-1 & BRCA-2, about their feelings on having their children screened in adolescence.

What was the result?
A strong majority felt they'd support more aggressive screening. No surprise there.

What's the controversy?
Is it right to burden teenagers with genetic information that they may not be able to properly understand or cope with. This topic of "genetic destiny" also predictably brings with it discussion of practical issues (Will I be discriminated against for getting a job or health insurance?) as well as discussion of ridiculous parallels (ie. Nazi eugenics).

I personally find the logic of not screening to be flawed. Carriers of the gene are predisposed to not only breast cancer, but also to ovarian, colon, prostate, and uterine malignancy among others. More aggressive screening tests and liberal use of prophylactic mastectomy would actually make a dramatic difference in cancer-specific mortality in this subset of the population.

Something to think about!

Rob

4 comments:

AA said...

The ignorance-is-bliss argument is horrible. Any rational person would much rather know. Sure, it's not good news, but knowing will lead people and their physicians to be more vigilant as you stated.

I really don't understand where people come up with these arguments.

Dr. Rob Oliver said...

I agree 100%. It's illogical to defer screening tests which could clearly dramatically lower subsequent breast cancer rates!

I know when you crunch the numbers there is a much clearer advantage for this then screening mammograms in the at large population

Doctor David said...

I totally agree with you that screening makes sense... but I see the logic in several caveats:

1. Future problems with obtaining health insurance (group coverage won't be a problem, probably, because that usually comes with just a cursory form to fill out, but for people who are not covered through work, knowing that they carry one of these mutations could make it tough to get insured).

2. You mentioned prophylactic mastectomy, but you also mentioned increased risks for other cancers, like ovarian.... so without evidence that these surgeries truly reduce cancer risk (and most mastectomies leave some breast tissue behind, as I'm sure you know), women could feel compelled to have prophylactic surgeries and yet not really change their risk appreciably.

3. There's a certain stress involved with knowing you carry a gene that puts you at risk for cancer (or any other disease... there's quite a literature related to this issue in people with Huntington's disease). The risks involved are complex and lead to difficult choices (like whether or not to have prophylactic surgery). So that means counseling has to go along with testing.

So... I agree with you that testing for BRCA1 and 2 mutations is a sensible thing to do, but it can't be just a check box on a form, the way we order a CBC. It needs to be done by a genetics counseling group, so the risks can be interpreted correctly, the decision to proceed with prophylactic surgeries will need to be guided by evidence, and (like all medical tests) it needs to be the patient's choice.

Dr. Rob Oliver said...

David,

in re. to your thoughful points

1. I'm convinced we're at the cusp of "medicare for all" in the US, which will remove the preexisting condition catch-22 that can exist in our system

2. Prophylactic mastectomy is extraordinarily successful at reducing risk of subsequently developing breast cancer in the high risk individual. As you mention, it's physically impossible to remove 100% of breast tissue (as it's invested in the subcutaneous fat junction), but a properly done mastectomy removes 98-99% of total breast mass(an estimate I've heard quoted)

3. Is genetic testing really that different then routine PSA testing or screening colonoscopy/PAP smears? I'd argue that your general surgeon should be able to coherantly discuss this with a patient, rather then sending them to some special "genetic counselor". This data re risk is pretty easy to figure using something like the "Gale model" which can be done in seconds.