Surgery is sometimes the only treatment needed for colorectal cancer, while at other times additional chemotherapy is also required. Now a new study shows that a blood test looking for cancer DNA can help identify the one in five people who may need chemo. William Nelson, director of the Kimmel Cancer Center at Johns Hopkins, explains.

Nelson: If you’re giving everyone that treatment only to go after 20% it’s going to be a hard numbers game. So what these folks tried to do is to use a blood test for DNA from the colorectal cancer that’s swimming around in the bloodstream. They did a randomized trial, more than 450 patients, either to get the additional chemotherapy, so called adjuvant chemotherapy based on the preference of the physician, 28% of them got that treatment. Versus, use this test if the colorectal cancer circulating DNA was gone, then they opted not to give the treatment.  :34

Nelson says outcomes were good for the folks who got the blood test. At Johns Hopkins, I’m Elizabeth Tracey.


A genetic form of colorectal cancer responds to treatment with a type of cancer drug known as an immune checkpoint inhibitor extremely well, a new study reveals. William Nelson, director of the Kimmel Cancer Center at Johns Hopkins, reviews the study.

Nelson: Since the inherited defect they had often presents an opportunity to use one of these immune checkpoint inhibitors and the one they used was called dostarlimab, so they got this drug as their only treatment before surgery. They wanted to see how well it worked and they wanted to go back in and rebiopsy and see if it wasn’t working why not. Much to their surprise it didn’t work very well, it worked incredibly well. All twelve of the people they treated so far, and the trial is ongoing, they’re accruing more people to it, had basically all the cancer disappear.  :31

Nelson notes that follow up so far is only several months, so additional time must pass to see how durable this stellar result remains. At Johns Hopkins, I’m Elizabeth Tracey.


Chemical groups called methyl groups can be removed from DNA by certain drugs used to treat cancer, but now a new study raises the possibility that in some people, such treatments unleash genes known to worsen cancer. William Nelson, director of the Kimmel Cancer Center at Johns Hopkins, explains.

Nelson: Some of the overmethylation is the way cancers stop genes that would otherwise be like the brakes on a car, so the cancer can just keep growing and growing. There are some drugs that interfere with the placing of these marks, so you reduce the number of methylation marks, hopefully unleashing the brake genes and you slow down cancer growth. This paper reports on two cohorts of patients who are treated with these kinds of drugs, and 30-40% of them it looks like there’s a gene that gets turned on at a higher level that might be generally dangerous.  :32

Nelson says careful genetic monitoring while treatment is underway may be the best strategy for detecting such an outcome. At Johns Hopkins, I’m Elizabeth Tracey.


You probably don’t think about sewage much but worldwide, many public health experts are increasingly turning to monitoring the stuff for infectious diseases, especially viruses. Stuart Ray, an infectious disease expert at Johns Hopkins, says this has been one of the lessons of the Covid-19 pandemic.

Ray: Sewage can be so valuable to us in epidemics, and I think it also underscores our learnings that we need for Covid, because this virus probably does infect the gut but maybe isn’t transmissible that way but it does leave a signature in sewage and so we can use that as a tool. So I think that we’re going to do more surveillance, and the power of molecular biology for all the things it’s doing for us. For managing cancer, for diagnosing all these things and so this is another example of molecular biology really changing the way we manage risk.  :30

Ray notes that the worldwide recognition of monkeypox is also being monitored in this way, and predicts that sewage surveillance will become standard practice going forward, helping in early recognition efforts of emerging infectious disease outbreaks and novel pathogens. At Johns Hopkins, I’m Elizabeth Tracey. 


As Covid infection continues apace, we have seen dramatic declines in flu and shifted patterns of other viruses, such as respiratory syncytial virus or RSV. Stuart Ray, an infectious disease expert at Johns Hopkins, attributes such changes to human behavior.

Ray: From a temperate zone life we think of flu as a winter virus, but in the tropics, the hot muggy times can be the peak of the flu season. So viruses don’t look at the calendar, but peoples’ behavior changes over time, and so there are a lot of dynamics that we ascribe to viruses, which are human behavioral dynamics. We saw that with the surges, that a lot of the surges couldn’t be explained by the seasons, they were explained in part by people getting relaxed and then the exponential growth of an infectious disease. We now have some learnings that we might be able to use to disrupt those patterns.  :34

Ray specifically notes that becoming more aware of when respiratory viruses of all types are increasing in transmission would also identify when wearing a mask might help. At Johns Hopkins, I’m Elizabeth Tracey.


 Masking reduces transmission of respiratory viruses like Covid-19 dramatically, yet naysayers abound. Stuart Ray, an infectious disease expert at Johns Hopkins, says one way to possibly overcome their objections is to provide an opportunity to really see what’s out there.

Ray: Leadership has not done a good job of helping people explore masks to find one that fits them well. Many people who have the means to try out masks haven’t done it but many people don’t have the resources and we really should be providing a wide range of masks to people and good education about how to know whether it fits well. In the hospital we do fit testing where we spray an aerosol, and we can tell whether or not the aerosol gets through the mask. Why don’t we have that in drugstores? And give people the chance to test a bunch of masks and find one that fits?  :30

Ray says other respiratory viruses such as the flu are also very effectively blocked by a properly fitted mask, and we could consider broadcasting public health alerts when viral transmission is high so people could choose to wear a mask then. At Johns Hopkins, I’m Elizabeth Tracey.


How did wearing a mask to prevent infection with a respiratory virus become so political? Infectious disease expert Stuart Ray at Johns Hopkins says he doesn’t know the answer to that, but thinks time will allow many of us to take a broader view of what we may still need to do to protect ourselves and others from Covid-19.

Ray: The current situation is that we have people who don’t yet have distance on it I think. People are still feeling very emotional about mask wearing, about other behaviors. So this is still a fraught time in dealing with this. Fortunately we have the tools now for people to keep themselves and their loved ones safe. Preventing transmission is a way of caring for others. I do think that people generally want to do well for the most vulnerable if they’re reminded, but sometimes we need to be reminded, and that you can’t look at someone and tell if they’re vulnerable.  :31

Ray says people who are immunocompromised and those with certain chronic health conditions may not look unwell but remain at high risk for Covid infection. At Johns Hopkins, I’m Elizabeth Tracey.