Two genes BRCA1 and BRCA2 are linked to hereditary breast

Observation: Two genes BRCA1 and BRCA2 are linked to hereditary breast cancer.

Plan: All women should be tested for these genes

Aim: Decrease the annual number of mammogram tests administered across a population and to more accurately assess a woman's individual risk of breast cancer

What is an assumption?
An assumption would be something that the plan assumes to be true for the aim to take place.

A. Some women who are tested for the two genes will subsequently undergo mammograms on a less frequent basis than they used to.

Correct. The argument is assuming that there will be a decrease in number of mammograms if women are tested for these genes. Only then can the aim of "decrease the annual number of mammogram tests administered across a population" materialise.

B. The majority of breast cancer patients have no family history of the disease.

This weakens our conclusion. It is not the assumption.

C. Researchers may have identified a third breast cancer gene that is linked with hereditary breast cancer.

Irrelevant.

D. Women who have these genes have an 90% chance of getting breast cancer while women who don't have these genes have only a 20% chance of getting breast cancer.

Certainly something that gives figures such as 90% and 20% cannot be an assumption. 0%, 50% or 100% can still play a role in certain questions but certainly not something like 20% or 90% until and unless these figures are mentioned in the original argument.

jabhatta2 - If the numbers were changed to 100% and 0% respectively, we don't NEED this to be true for our conclusion. We just want to reduce the number of tests. As long as the genes are indicative of probabilities, our argument is fine. We are looking to reduce the number of tests, not abolish them altogether.

E. The presence of BRCA1 and BRCA 2 can explain upto to 50% of hereditary cases.

Again, we don't need them to explain upto 50% of hereditary cases. They could explain only 30% or they could explain 70%. As long as the genes do explain some hereditary cases, our argument is fine.

Answer (A)

I'll try to give this question a shot, I narrowed down to A and D but did not find D useful after negating it..

BRCA1 and BRCA2 <----> breast cancer.
All women should be tested for these genes ---> DECREASE the annual number of MT and accurately ASSESS risk of breast cancer,

Goal: REDUCE no. of MT and ASSESS accurately risk of breast cancer
Any choice post-negation, should counter these goals.

Lets negate A,
A. Some women who are tested for the two genes will NOT subsequently undergo mammograms on a less frequent basis than they used to. =
Implies that some women tested for the 2 genes WILL undergo MT on a FREQUENT basis than they used to
This will lead to increase in the MT.
Conclusion doesn't stand. (This may be a little weak bc of usage of "some women" but still the best of all)

D. Women who have these genes have 90% chance of getting breast cancer while women who don't have these genes have only a 20% chance of getting breast cancer.
Negating this choice will not have significant impact on the conclusion for e.g. Women who have these genes DONT HAVE 90% chance of breast cancer then what is their chance of getting cancer ? We simply dont know.

Hi can someone confirm if my understanding is clear?
If let us say there are 100 womans who are tested for these genes. Out of them let us suppose 50 tested positive for these genes but the other 50 got negatively tested. Then that mean the negatively tested women will not go as frequently as they used to prior ? is that how A is correct? First testing of genes happen and then mammograms, right? These are two different processes? Correct?

bEST,
mK

mk96
BRCA genes are basically BReast CAncer genes (when mutated, they destroy cells)
So 50 women who've been tested negative for BRCA-1/BRCA-2 genes undergo Mammogram tests LESS FREQUENTLY.

For example,
Each of the 100 women went for mammogram tests 5 times per year
So the total annual no. of mammogram tests = 500 / yr

Now after the gene testing for all 100 women,

Each of the 50 women tested positive for these genes will undergo mammogram test 5 times annually, just like before.
Total no. of mammogram tests for +vely tested women = 250

BUT,
Each of the 50 women tested negative for these genes will undergo mammogram test twice a year (LESS FREQUENT)
Total no. of mammogram tests for -vely tested women = 100

Total no. of mammogram tests for all women = 350 / yr
So by testing genes we have assessed risked accurately and reduced no. of mammogram tests by 150.

I think I am going through the argument with the same thought process. And this is stemming from the fact that we aren't sure what Mammograms 100% do. Googling it says that it is an X-ray that finds early detection of cancer or other issues. Now, if the women who KNOW that they have the 2 genes, then wouldn't they be testing more often? Or does knowing that a person has these 2 genes means that they will need to take another test other than Mammogram?

Thank you KarishmaB for the great explanation.

My question is regarding option B. In question stem, it says "Hereditary disease" and option B talks about "family history of disease". Can't we just discard this choice this basis only because we already know that the disease is [hereditary == family history of disease]. So this statement is not adding any new information.

Conclusion: To REDUCE the no.of mammograms & to assess risk -> Test has to be done
Which of the following is the assumption?

A. Some women who are tested for the two genes will subsequently undergo mammograms on a less frequent basis than they used to.
These tests reduce the no.of mammograms
B. The majority of breast cancer patients have no family history of the disease.
Weakens the conclusion, as testing all the women for these genes would futile
C. Researchers may have identified a third breast cancer gene that is linked with hereditary breast cancer.
Irrelevant
D. Women who have these genes have an 90% chance of getting breast cancer while women who don't have these genes have only a 20% chance of getting breast cancer.
Even though the risk levels are known, it doesn't reduce the no.of mammograms administered
E. The presence of BRCA1 and BRCA 2 can explain upto to 50% of hereditary cases
Addresses the accuracy part but not the no.of mammograms part

OA l8r[/quote]

Here is why I think D is wrong:

"Women who have these genes have an 90% chance of getting breast cancer while women who don't have these genes have only a 20% chance of getting breast cancer."

Women who have these genes have a 90% chance of getting breast cancer : ok, this does not mean that these women definitely have cancer. There is a high likelihood that they might be develop cancer in the future. Thus with annual mammogram testing, these women can be track the presence of cancer in their body. Thus, the annual mammogram testing does NOT decrease.

women who don't have these genes have only a 20% chance of getting breast cancer : so women who don't have the aforementioned genes have a 20% chance of developing cancer. Does that mean that these women should not annually perform mammogram testing to track their health? No, there is still a 20% chance these women could develop cancer. So they would still need to perform the mammogram tests. Thus, the annual mammogram testing does NOT decrease.

Therefore Option D is irrelevant