A Primary Care Physician Explores Barriers to Cancer Prevention and Clinical Trial Accrual

A Conversation With Carmen Guerra, MD

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To accelerate progress in the survival rates of people with cancer in the United States and to reduce cancer disparities across the entire spectrum of cancer from diagnosis to survivorship, there needs to be increased access to cancer screening and prevention programs. To shed light on this critical issue, The ASCO Post recently spoke with Carmen Guerra, MD, Founding Co-Director of the University of Pennsylvania Health System Colorectal Cancer Screening Navigation Program and the Penn Breast Health Initiative/Healthy Woman Program. In 2017, Dr. Guerra received the American Cancer Society Cancer Control Career Development Award and the St. George National Award.

Carmen Guerra, MD

Carmen Guerra, MD

Professional Background

Please tell our readers a bit about your current position.

I am a practicing primary care physician and am on the faculty of the Perelman School of Medicine. I’m also Vice Chair of Diversity and Inclusion for the Department of Medicine and Associate Director of the Office of Diversity at the Abramson Cancer Center of the University of Pennsylvania, where I specialize in building programs in cancer control, especially eliminating the barriers to cancer screening tests in vulnerable and underserved minority populations. To that end, I’ve conducted federally funded and foundation-funded research largely in colorectal and breast cancer screening. I also serve as a scientific officer on the board of the American Cancer Society.

HPV Vaccination: Slow Uptake in the United States

With the advent of human papillomavirus (HPV) vaccines, cervical cancer is largely preventable, yet dissemination, especially among underserved populations, lags behind countries such as England and Australia. Why is this vaccine not being used to its full capacity?

Yes, that’s an interesting phenomenon, given that all three countries began HPV vaccination programs around the same year, 2006. Australia is actually on track to completely eliminate cervical cancer within a couple of decades. Unfortunately, although genital HPV infection rates in the United States are high, surveys show that less than half of our teenagers are vaccinated.

The reasons for this slow uptake of vaccinations are multifactorial sociopolitical decisions. For one, as of 2017, only two states—Virginia and Rhode Island—have mandated HPV vaccinations for teenagers. Given the politics and demographics of our country, we have a patchwork of states and districts that don’t have uniform public health laws.

There are also cultural challenges in our diverse populations that create barriers to HPV vaccinations, such as the ill-founded fear that vaccination will encourage increased sexual behavior. Then, we see the provider issues in which many busy primary care doctors may not take the opportunity to discuss vaccination.

There was a Centers for Disease Control and Prevention study looking at this problem; from the data collected, the reasons individuals refused vaccinations were fear of side effects and medical safety. A percentage of the people surveyed did not even know the vaccine existed or did not receive a provider recommendation. It’s important to note that although the vaccination rate success we’ve seen in Australia is laudable, it is basically a homogeneous nation, with a population of just 25 million.

I was part of the team that developed the American Cancer Society cervical cancer vaccination recommendations that we published this year. We recommend that individuals with a cervix initiate cervical cancer screening at age 25 and undergo primary HPV testing every 5 years through age 65 years (preferred). If primary HPV testing is not available, individuals between the ages of 25 and 65 years should be screened with cotesting (HPV testing in combination with cytology) every 5 years or cytology alone every 3 years.

Are you aware of any innovative work in this area?

Yes, in fact, we have a doctor here at Perelman, Alex Fiks, MD, MSCE, who developed an electronic medical record–based HPV vaccine decision support intervention targeting clinicians (immunization alerts, education, and feedback) and families. It had enormous success, and he is now going to implement this strategy nationwide through a government-funded program. So, we’ve identified the barriers, now it’s up to us to implement strategies like the one Dr. Fiks has developed.

Colorectal Cancer Screening: When to Start

You participated in a 2018 ASCO GI committee that debated the American Cancer Society recommendations for colonoscopy. Please tell us about that.

We were concerned about the rising rates of colorectal cancer among younger patients and debated whether or not to lower the screening guideline recommendation of initiation of regular screening at the age of 50. I was on the side that wanted to lower the age of screening initiation to 45.

During the question-and-answer session, a woman went to the mic and told me that she ran a support group for colorectal cancer survivors; her youngest participant was 19 years old, and my heart sank to the floor. She pleaded with the panel to encourage primary care doctors to be especially attentive when their younger patients present with symptoms such as rectal bleeding and not dismiss it as something benign such as hemorrhoids or a small rectal fissure.

After the session, I walked out with one of the panelists who’d argued to maintain the American Cancer Society recommendation of 50 years, and we had a productive conversation. The data show an increase in younger patients presenting with colorectal cancer. We both agreed that primary care physicians need to be more aware of mild symptoms and predispositions that might indicate potential colorectal cancer in their younger patients.

Clinical Trial Accrual

Adult accrual in clinical trials remains very low. Please describe the barriers here and any possible solutions.

This is such an important issue. ASCO has requested information from primary care physicians about how to improve our accrual to clinical trials among our minority patients with cancer. I just submitted my recommendation to ASCO. There is no magic bullet that will solve this challenge. We need a multifaceted approach that examines the barriers that exist within the patient populations, the medical community, and medical organizations—in effect, one that engages all of the separate stakeholders. On the patient level, and there is much about this in the literature, there is a lack of awareness about the design and goals of clinical cancer trials. One of the prevailing attitudes is the “experimental guinea pig” false belief.

"We have a lot of work to do in bridging the knowledge and awareness gap before we see better rates of minority enrollment in clinical trials."
— Carmen Guerra, MD

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We find a long-standing distrust among minorities about medical research, given some of the historical incidents. There are also barriers created by out-of-pocket costs and life disruptions that come into play. So, we have a lot of work to do in bridging the knowledge and awareness gap before we see better rates of minority enrollment in clinical trials. I’m glad ASCO is taking the lead on an issue that has a huge impact on the oncology community.

Role of Telemedicine

During the COVID-19 pandemic, the Internet has evolved as a valuable doctor-patient interface. Can this technology help in the areas of early detection and connecting underserved populations?

For one, the pandemic accelerated our realization that Internet access is absolutely critical for the delivery of health care in today’s challenging environment. I coauthored a piece for The Philadelphia Inquirer called “Why Internet Access Is a ‘Super’ Determinant of Health.”1 We pointed out that about 21.3 million Americans, or 6.5 % of the U.S. population, live in a digital desert and lack access to broadband Internet service. Without Internet access, people are unable to communicate freely with their physicians, to access electronic medical records, to research health conditions and treatment, or to find resources for healthy behaviors and lifestyle changes. So, the COVID-19 pandemic has demonstrated how valuable the Internet is and also illustrates a digital disparity that needs attention.

Intersection of Primary Care and Cancer Care

As a primary care physician working in the oncology sector, do you see an evolving role for primary care in cancer care?

I do, especially in the survivorship setting, in which the primary care doctor could partner with the oncology team to ensure patients’ care is properly coordinated. We know primary care providers usually have had longer relationships with patients with cancer, so they may be more in tune with the patient’s desires. However, unfortunately, this synergistic relationship has been slow to evolve. Part of the reason may be that many primary care doctors don’t feel qualified to fully integrate into the complex oncologic care model. Moreover, patients with cancer become very attached to their oncologists, who they’ve entrusted with their lives, so we need to find ways to create care models in which primary care physicians can integrate into the continuum of oncology care. It would help create better outcomes and also add value to the care delivery system. 

DISCLOSURE: Dr. Guerra has held leadership roles in Freenome and Guardant Health; holds stock or other ownership interests in Beam Therapeutics, CRISPR Therapeutics, Editas Medicine, and Intellia Therapeutics; has an immediate family member who has received honoraria from Lundbeck; has an immediate family member who has served in a consulting or advisory role for EB Squibb; has an immediate family member who has participated in a speakers bureau for Janssen and Pfizer; has received research funding from Bristol Myers Squibb; and has an immediate family member who has been reimbursed for travel, accommodations, or other expenses by Janssen and Lundbeck.


1. Guerra C, Millstein J, Vega R: Why Internet access is a ‘super’ determinant of health. The Philadelphia Inquirer, July 7, 2020. Available at Accessed September 21, 2020.