Do clams get cancer? Questions from High School Freshmen

One of my favorite outreach activities is volunteering at public schools. Over the years, I’ve had the opportunity to speak to and work with elementary, middle, and high school students – doing everything from dry ice demonstrations, mini anatomy labs with fixed mouse organs, microscopy labs with tissue sections, and career talks. Most recently, I visited a local MNPS high school to talk about cancer biology (click here to see the slide show and an explanation).


First of all, I was super impressed by how much these young people already knew! They’re studying cell biology and cell division right now, which worked well for my talk about how errors in DNA replication, mutations, and failed repair after damage leading to amplifications and deletions contribute to cancer. We used cell cycle regulation as an example, talking about oncogenes (drive cancer growth) and tumor suppressors (normal braking system for growth – lost in many cancers) that encode cell cycle regulators. They already knew much of the background, including how the cell cycle is controlled, the steps involved, and some of the proteins that regulate it. They also knew a lot about carcinogens (e.g. cigarette smoke, ultraviolet radiation from the sun, certain chemicals), treatments (chemotherapy and radiation), and certain types of cancer including breast, lung, and colon cancer.

Secondly, they were engaged and asked a LOT of questions. It made the presentation much more fun and interactive, and it gave me quite a bit to think about. There were, of course, questions I could not answer off the top of my head. But I promised the students I would look up answers to their questions and send the answers to their teacher. These are some of those questions:

1. What is the rarest form of cancer?

The latest statistics I could find from the American Cancer Society are from 2017. According to the data they gathered, the rarest cancers diagnosed in the adults (20+ years old) in the United States include cancers of the trachea, Kaposi sarcoma (this one is interesting because it led to the discovery of HIV – when more of these cancers cropped up in young gay men in the 1980s, it led investigators to start studying this population to identify the cause), lip, nose cavity and middle ear.

2. Can cancer in a transplanted organ spread to a new host?

Photo credit Deposit Photos

This has actually happened! In 2018, it was reported that a 53 year old woman who died from a stroke and had no known medical conditions at the time of her death (including screens for cancer) had her organs transplanted into at least 5 recipients. The patient who received the heart died shortly after transplant from unrelated causes, but a year and a half later, the patient who received lungs from the donor became ill and was found to have breast cancer cells in her body with DNA that matched the original donor. She died shortly after. The patient who received the donor’s liver developed breast cancer in the transplanted organ in 2011, was treated, but died of a recurrence in 2014. The patient who received the donor’s left kidney developed and died from breast cancer in 2013 (six years after transplant), and the patient who received the donor’s right kidney was diagnosed with breast cancer in his kidney cells in 2011 – they were able to remove the tumor from the kidney, and after treatment the patient lived 10 years cancer free (at the time of reporting).

This phenomenon is very rare, however, and most of the time cancer in a potential donor can be detected by screening before organ harvest.

3. Do clams or reptiles get cancer?

Photo credit Vale’ Tamblay

Apparently, clams do get cancer. Even worse, for at least one type of cancer, the cancer cells from one clam can travel to another clam through water and grow in the new host. Yikes!

Cancers have been documented in reptiles, but they are much more under-studied than mammals and other animals. More research may be done to better study the link between cancer and metabolism, since metabolism is lower/slower in ectotherms (cold blooded creatures) than endotherms (warm blooded creatures).

Interestingly, elephants and naked mole rats rarely, if ever, get cancer, and ongoing studies into their physiology and genetics could help us figure out why and how we can use the knowledge to prevent cancer in humans.

4. Can babies be born with cancer?

It is rare, but it can happen. There have been reports of babies born with neuroblastoma, leukemia, and teratomas.

5. When did people start getting cancer?

(I actually knew part of the answer to this one, but it was fun to dig a little deeper)

Photo credit Deposit Photos

The world’s oldest recorded case of cancer came from ancient Egypt in 1500 B.C., and it was recorded that there was no treatment for the cancer, only palliative treatment (relief of pain and suffering). Cancer has been with us much longer, though, given that bone cancer (osteosarcoma) has been detected in fossils from early hominids dated to 1.7 million years ago. Similar tumors have been found in fossils from dinosaurs and even from ancient turtles that lived 240 million years ago!

Got any questions for me? Send them! I’ll do my best to find the answers and more information. Knowledge is power! Hit me with your burning questions – the weirder the better!

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