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Why Cancer Screening Has Never Been Shown to Save Lives

Vinay Prasad, MD and Andrew Buelt, DO
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Cancer screening is supposed to save lives, but does it actually meet that goal? 

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Ian L., Dr -

Screening works for Hypertension it seems so why not other disease states .?
The question recolon cancer needs to be screening from age 40-55 does it prolong life ?
Intuitively a 20mm Villous polyp found in a 50 year treated would extend life .
A 45 year old with Gleeson 8-10 prostate cancer treated with the modalities would I believe have his life extended.
A 40 year old women with breast cancer found on ultrafast MRI likely would have an extended life .
No one ought nowadays ought do a prostatectomy on a Gleeson grade 5 -6 60 year old male and the biopsy of choice is becoming perineal under MRI guidance .
Reference : Sepsis and 'Superbugs' Favour transperineal approach over transrectal approach for prostate biopsy :Grummet JP et al BJU Int 2014 Sep :114(3):384-388.

Jacob D., MD -

I'm having a hard time wrapping my head around this one. Say a women in her 30s feels a lump in her breast that turns out to be malignant and has it removed. Wouldn't that in theory extend her life? or is this not considered screening? Also, what about a women with a family history of breast cancer, BRCA1/2 mutations who is encouraged to undergo screening mammography at 30 years of age? Could this extend their life?

Heidi J., MD -

Hey Jake - You raise a really good point: the difference between general population screening and screening in individuals with risk factors for specific diseases. In this chapter, Dr. Prasad was referring to population screening, which is defined as "a strategy used in a population to identify the possible presence of an as-yet-undiagnosed disease in individuals without signs or symptoms. This can include individuals with pre-symptomatic or unrecognized symptomatic disease. As such, screening tests are somewhat unique in that they are performed on persons apparently in good health" (Wikipedia, yep, Wikipedia - they define it better than the journals do!). Those with specific risk factors, such as the woman with FHX breast CA, and BRCA 1/2 mutation, would fall in a different risk category and should be screened differently than the average person. Recommendations for screening high risk patients are presumably based on improved disease specific morbidity and mortality.

Heidi J., MD -

Re Breast Cancer screening, you may want to check out our January 2015 on screening mammography for a deeper dive.

Jacob D., MD -

Thanks Heidi. I went back and re-read the notes from January 2015 on screening mammography. Obviously, I have my own biases, but I just don't understand how and why we are still doing mammograms? It's frustrating that mammograms are a quality measure in most family practice offices. My wife, who is 37 years old, 10 weeks postpartum with our first child , and exclusively breast feeding noted a lump in her breast that seemed to get a little bigger since breast feeding. Her PCP ordered an US that showed benign findings, then referred her to a breast specialist, who discovered another lump on the opposite breast, ordered an US that showed benign findings, but wants her to have it followed up in 6 months. My wife's maternal aunt had breast cancer (not sure what type, but she's still alive), and according to the Gail model risk assessment, it wouldn't even affect her risk. Thankfully we've met our deductible, but I feel like a lot of healthcare dollars have been wasted and created anxiety in my wife. As a woman, do you plan on having a screening mammogram?

Heidi J., MD -

Hey Jake -
Ah, sorry to hear about the recent events; sounds stressful - especially with a newborn in the mix! On both a professional and personal level, I hope that decisive evidence is soon available and that professional bodies issue guidelines in accordance with the best science. It's a grey zone for many of us....

Arsalan H. -

This was an interesting article. I'm really curious if anyone has looked at morbidity. Does cancer screening improve QALY's or DALY's?

Heidi J., MD -

Hi Arsalan - Excellent, excellent question. We're on it - stay tuned!!

Ian L., Dr -

In FAST MRI breast screening revisited MJain A Jain Hyzy G Werth : screening 591 High Risk Women with an abbreviated protocol Realised a negative predictive value of 99.8% : Journal of Medical Imaging and Radiological Oncology July 2016 .
This test is available .
Could be useful for women dense breast tissue who have been on oral contraceptives for Ten years plus have Smoked 10 pack years Drink Two standard drinks or more per day .One first degree Relative Breast Cancer .

Stephen E. -

In this talk, Dr. Prasad says we would need a study of 1-4 million people to power a study that could adequately answer the question "Does cancer screening improve overall mortality?" Because we don't have a study that large, it seems that it should come at no surprise to him that we don't have any RTCs that have proven any specific cancer screening improves overall mortality. Not sure how he came up with that number (I'm sure there's some killer number crunching behind it), but if that's true, by my interpretation, it would be accurate to tell patients, "Cancer screening might save lives, we just haven't had good enough studies to have a chance to prove it yet." It seems that it would be somewhat misleading to say "Studies don't show any overall mortality benefit," because as of now, we haven't had big enough studies to expect to prove so. Is that a fair conclusion from this talk? That being said, it seems his biggest point is that we need to fund these studies because any 100 billion dollar/year industry should have good evidence.
-curious resident in Ohio who's still trying to learn to communicate to patients why they should take the medicine I'm confident they need, much less have effective cancer screening counseling sessions.

Heidi J., MD -

Hey Stephen - Excellent point! Hopefully those studies will be done. I've passed along your comment to Andrew Buelt and Dr. Prasad, so stay tuned for more.

And, I loved your humorous sign off ;) Those sorts of conversations do get easier, except the evidence keeps changing & that's hard to explain to your patients too! (My poor patients have been through many iterations of my lipid spiel...)

Thanks for your comment and for listening,

Judith H. -

A bit of a delayed response here from Vancouver...we were taught in medical school that deaths from cervical cancer are far more common in countries without a screening program than in countries with, and I had the impression that of all the cancer screening programs, this was the one that most convincingly reduced overall mortality. I did a quick google scholar search and didn't find any compelling evidence near the top of the heap, but did find that the USPSTF 2012 cervical cancer screening guidelines state that "Cervical cancer deaths in the United States have decreased dramatically since the implementation of widespread cervical cancer screening. Most cases of cervical cancer occur in women who have not been appropriately screened" (citing 2 reports by Vesco KK et al 2011- evidence reviews prepared for the USPSTF). My guess is that it would be hard to do an RCT for cervical cancer screening that involved a no-screening arm b/c the epidemiological evidence is felt to be too convincing to ethically justify a no-screening arm. I would have been interested to hear Dr Prasad's thoughts on cervical cancer screening and what he would tell patients.

Heidi J., MD -

Excellent question, Judith! We've passed your question along to Dr. Prasad & will keep you posted.

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Ear Pain is but a Memory Full episode audio for MD edition 183:12 min - 86 MB - M4AHippo Primary Care RAP December 2016 Summary 305 KB - PDF