An overview of cancer screenings, part 1

Cancer is certainly among the cruelest of the major chronic diseases, as in so many circumstances its emergence can be the product of little more than bad luck. Truthfully, we know little in the way of cancer prevention outside of avoidance of carcinogens and various carcinogenic behaviors and risk factors, such as smoking or obesity. Since so little of this is within our control, this places all the more emphasis on screening as a means of catching any disease process early enough to avoid it becoming too advanced.

Unfortunately, for several kinds of cancers, we don't have an effective means of screening just yet. Exciting things like advances in MRI technology and DNA testing, including liquid biopsies, are on the horizon, but in the meantime, we are limited to a few reasonably reliable techniques for some common cancers. Here, we’ll give an overview of the big five can't-miss cancers you should be considering in your screening regimen. For each one, we’ll go over the United States Preventive Services Task Force (USPSTF) guidelines, as well as our personal takes.

1. Colorectal

On this one, I am willing to make quite a big claim, which is that virtually no one should be dying of colorectal cancer in 2025. We have such good screening strategies, and one gold standard strategy in particular, that it is seemingly inexcusable not to pick up on this at a stage where it can be effectively treated. Let’s start with the USPSTF guidelines. Recently, in light of increasing data surrounding younger populations getting colon cancer, the USPSTF lowered the age of starting screening recommendation from 50 to 45; they then recommend that individuals screen through the age of 75. For screening strategies, they recommend a colonoscopy once every ten years, a stool FIT test every year, or a stool Cologuard test every three years. Other less common strategies include a flexible sigmoidoscopy or CT colonography every five years. They also offer the possibility of stacking screening modalities, such as performing a stool test every year with a colonoscopy every five years.

For starters, let's give our take on the different tests. The clear gold standard here is colonoscopy, as it has by far the highest sensitivity for picking up cancers. This makes sense as this is the only method which allows a provider to directly visualize the inside of the colon where tumors grow and actually remove cancers that they see; therefore, it is both diagnostic and therapeutic. Note that each of the other screening modalities is merely a precursor to colonoscopy, should they produce a positive test. That is, a positive result on Cologuard sends someone to get a colonoscopy to find the lesion and resect it.

The reality is, for virtually all of these screenings, we can't give broad, sweeping recommendations on an age to start and frequency with which to do it, as they are highly situation-dependent. For example, one with a family history of colon cancer, or previously found high-risk polyps would screen a lot earlier and/or more frequently than one without. However, for colon cancer screening, I would emphatically recommend colonoscopy and having a thoughtful conversation with your provider about appropriate ages and frequencies to start it. One thing is for certain: the current guidelines outlined by the USPSTF are not nearly aggressive enough or early enough, particularly given the increase in prevalence among younger age groups. Be sure that in your provider, you truly see an advocate for proactivity with screenings and overall disease prevention. These are critical components to look for in general when selecting a primary care physician, and small provider details that could seriously alter the course of your life and health.

2. Breast

For breast cancer screening, the USPSTF recommends mammography every two years starting at age 40 for women of average risk. Of course, with the family history of breast cancer, other predisposing risk factors, or personal cancer history, it is recommended to start earlier and screen more frequently. Many cancer societies of physicians, as well as other medical organizations, are even recommending or practicing annual screening for all, including most within primary care at the Mayo Clinic. Again, we encourage you to be engaging in thoughtful conversations with your PCP regarding age of starting screening and frequency. That said, when it comes to breast cancer screening, we encourage folks to be bolder in a different aspect other than their aggression with timing of screening.

The main insight here is that, while mammography is a really good test, it tends to not work as well in women with dense breast tissue, as this can make it harder to pick up on lesions of similar intensity on the scan. This now is a really good use case for stacking modalities, and adopting a Swiss cheese approach to screening. That is, you want to think about the situation as stacking up pieces of Swiss cheese. Each individually has holes because they are imperfect tests, but when stacked on top of each other, they have much fewer holes to get all the way through. The first layer of Swiss cheese in breast cancer screening is undoubtedly mammography, followed by alternative modalities such as ultrasound or diffusion-weighted MRI in women with dense breast tissue. Particularly with the increasing prevalence and affordability of ultrasound, this additional layer of security feels like a no-brainer, and I would expect it to increasingly become common practice in primary care settings.

As usual, I'm noticing that this post is turning out to be far more detailed and lengthy than I was anticipating, so we may have to leave things there for today and pick back up with the other common screenings next time, which include cervical, prostate, and lung. The key takeaways for now: always ensure your provider is properly advocating for you and demonstrating care in suggestions of screening onset, frequency, and modality. Do not be afraid to ask your provider honest questions, including when it comes to proposing additional screening outside of guidelines when it comes to these parameters. That said, if you are hoping for screening for alternative forms of cancer, unfortunately, that is not mainstream or even taking place in progressive practices at present (i.e. there are no specific screening recommendations or reliable strategies for pancreatic cancer, or testicular cancer, or blood cancers, or brain cancers, other than regular general medical exams). Some are engaging in full body MRI practices to pan-scan the body for malignancies, but these may come with their own issues (particularly with false negatives) and discussion on this topic ought to be reserved for a future post. Additionally, exciting cell-free DNA detection strategies called liquid biopsies may soon be a common option to screen a wide array of cancers with a simple blood test, however these are yet to be well-established as a means of screening. In the meantime, stick with us for these following major modalities to be outlined in my next post. 

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