In the late 70s, scientists discovered that the body contains certain cancer-causing genes, which if mutated, lead to the development of cancer. This discovery unleashed a flurry of research in which scientists tried to identify genes that could be directly implicated in cancer. Scientists found one such gene – the HER2 gene – which is overexpressed in about 20% of breast cancers. This cancer was thus named HER2+ breast cancer. It is a particularly aggressive form of breast cancer; it typically does not respond to traditional chemotherapy, and patients with HER2+ breast cancer have a higher likelihood of cancer recurrence.

The HER2 gene codes for the HER2 is a receptor which, along with other receptors, plays an important role in regulating a variety of (sometimes contradictory) processes including cell growth, cell proliferation, and apoptosis (cell death when something in the cellular machinery goes very wrong). In normal cells, the activity of HER2 and the associated cell-signaling pathways is very strictly regulated.

The mutation causing this cancer leads to an overexpression of HER2 receptors, which in turn leads to the activation of signaling pathways that enhance cell survival and the suppression of the action of proteins that prevent the growth of damaged cells, both of which lead to the formation of tumors.

While most chemotherapy treatments have been ineffective at treating HER2+ type breast cancer, targeted immunotherapy in the form of trastuzumab has been effective in improving outcomes. Trastuzumab is a monoclonal antibody that binds to the HER2 receptor, which prevents HER2 from binding to the other receptors that are necessary for the activation of the signaling pathways that lead to tumor growth. The antibodies also activate the body’s immune system, which recruits cells that release cytotoxic chemicals into the environment surrounding the tumor cells, ultimately killing them.

While trastuzumab has improved the prognosis of HER2+ breast cancer patients – in some studies, the median overall survival has increased by nearly 5 years – many patients develop resistance against trastuzumab. This is often because the shape and structure of the HER2 receptor in tumor cells undergoes a change, due to which trastuzumab can no longer bind to HER2 and can no longer prevent it from activating signaling pathways. Further research into different targeted drugs is currently underway and in 2019, the Food and Drug Administration (FDA) approved another antibody, atezolizumab, to treat breast cancer.

References:
More on the discovery of the HER2 gene: https://www.gene.com/stories/her2/
How trastuzumab works: https://www-nejm-org.proxy.library.emory.edu/doi/full/10.1056/NEJMra043186
More on immunotherapies to threat HER2+ breast cancer: https://www.nature.com/articles/s41523-020-0153-3

Around 1 in 8 women in the U.S. will develop breast cancer in their lifetime. Cancer happens when abnormal cells grow and divide uncontrollably. Though breast cancer primarily appears in women, men can actually get breast cancer too and are affected by the same types of breast cancer as women. About 1 in every 100 diagnosed case of breast cancer in the U.S. affects men. Breast cancer becomes particularly dangerous when it spreads outside the breast through blood and lymph vessels, a process called metastasizing.

The most common type of breast cancer is Invasive ductal carcinoma, where cancer cells begin in the ducts that bring milk to the nipple. Many breast cancers also start in the glands that make milk, called invasive lobular carcinoma. It is unclear why some people get breast cancer while others do not. However, research has indicated certain risk factors for breast cancer including age, genetic mutations, and family history. Other factors surrounding lifestyle include not being physically active, taking hormones, and drinking alcohol.

Some symptoms of breast cancer are lumps in the breast or underarm, nipple retraction, irritation of the breast skin, and nipple discharge.  Mammograms, X-rays of the breast, can be used to detect small tumors in the breast before the tumors are big enough to see or feel. In addition to mammograms, doctors may also use breast ultrasounds, and MRIs to diagnose breast cancer in certain patients. Doctors may also use a biopsy, a test that removes fluid from the breast to perform further testing on. Treatments are chosen based on the type and severity of the cancer. Most breast lumps come from non-cancerous conditions such as fibrocystic condition, which causes breast tenderness, and cysts, small growths filled with fluid.

There are many treatments for breast cancer, and patients often get multiple different treatments. Chemotherapy uses medicine to kill cancer cells. Radiation energy uses intense energy beams to kill cancer cells. Hormonal therapy blocks estrogen receptors on breast cancer cells. Surgery can also be used to cut out cancerous tissues. Patients will meet with their oncologist to develop a treatment plan combining different types of treatments. For early-stage invasive cancers, doctors usually recommend surgery. For larger cancers, doctors usually recommend chemotherapy or hormonal treatment before surgery. After surgery, doctors often recommend adjuvant therapy to lower the risk of recurrence and can include radiation therapy, chemotherapy, targeted therapy, and hormonal therapy. Some patients also use a tumor board, a group of medical experts on cancer who work together to find a treatment plan.

Breast cancer death rates are higher than other types of cancer. It is also the most common type of cancer in women, accounting for 30% of all diagnosed cancers in women. Luckily, the breast cancer death rate is decreasing because of advances in treatment and the ability to detect breast cancer earlier through better screening.

Sources:

• https://www.mayoclinic.org/diseases-conditions/breast-cancer/symptoms-causes/syc-20352470
• https://www.cancer.org/cancer/breast-cancer/about/what-is-breast-cancer.html
• https://www.cdc.gov/cancer/breast/basic_info/what-is-breast-cancer.htm
• https://www.cancer.gov/about-cancer/understanding/statistics
• https://ascopost.com/news/february-2021/have-breast-cancer-mortality-rates-stopped-declining-for-younger-women/

Within marrow tissue found in the center of bones, the body produces red and white blood cells, which are critical to transporting oxygen and fighting off infection. Certain types of cancers can cause serious damage to bone marrow, leaving patients without the blood cells needed to perform these important functions. Using stem cells from either the patient or a donor, doctors can now replace this tissue and allow patients to begin forming their own blood cells again. This procedure, which is known as a bone marrow or stem cell transplant, can be lifesaving for cancer patients.

Stem cells are cells within the body that can grow to serve as most other types of cells. They serve as a natural repair system for the body, allowing it to replace cells that are damaged beyond repair. Adult stem cells are commonly found in bone marrow and can be used to create new bone marrow tissue. Once implanted within bone marrow, the stem cells divide and modify themselves to form specific functions.

Stem cell transplants are most often used for patients with leukemia and lymphoma, cancers that directly attack bone marrow tissue. They can also be used to replace bone marrow damaged by very high doses of chemotherapy and radiation therapy used to treat other cancers. Once the patient receives an initial high dose of radiation or chemotherapy, they can then begin to receive the transplanted stem cells. The stem cells are injected directly into the patient’s bloodstream through an IV. Once inside the bloodstream, the stem cells then make their way to the damaged bone marrow tissue and begin to implant and grow. Over several months, the body begins to form new blood cells. It can take several months for red blood cell counts to be replenished, and up to two years for the immune system to fully recover.

Stem cell treatments fall into two specific categories depending on the source of the new cells. In autologous transplants, the cells come from undamaged tissue in the same patient. This technique is often used on cancers that do not directly attack the bone marrow tissue. Before chemotherapy or radiation therapy, bone marrow tissue is taken from the patient. Once this initial therapy is complete, the tissue then can be injected back into the patient, allowing the bone marrow to regenerate. Autologous transplants are preferable in many circumstances since the body recognizes the newly introduces tissue and does not mount an immune response as a result.

However, in cases of cancer such as leukemia that attack marrow tissue, patients may not have undamaged marrow tissue to collect. In these cases, a transplant from another donor becomes necessary. These cases are known as allogeneic transplants. In an allogeneic transplant, patients are matched with donors by human leukocyte antigen (HLA) type. HLA are proteins that exist on most of the body’s blood cells and help the body distinguish normal cells from foreign ones. Having a similar marker reduces the chances that the patient’s immune system will reject the cells, a condition known as Graft versus host disease (GVHD).

For an allogeneic transplant, a patient’s blood is first sampled to determine the HLA type. The patient is then matched with a donor, a process that can take several weeks. While the best donor is generally an immediate family member, 75% of patients do not have a suitable donor in their family and require an unrelated donor. These donors can be located through national registries such as the National Marrow Donor Program.

Stem cell transplants play an important role in treating cancers that damage bone marrow as well as in complimenting other types of cancer treatments by mitigating harmful side effects. Using modern technology, these transplants can be completed quickly and minimally invasively. Although the recovery process can be long, stem cell transplants allow many patients to eventually resume normal, healthy lives.

References:
https://www.mdanderson.org/treatment-options/stem-cell-transplantation.html
https://www.cancer.net/navigating-cancer-care/how-cancer-treated/bone-marrowstem-cell-transplantation/what-bone-marrow-transplant-stem-cell-transplant
https://www.webmd.com/cancer/cancer-stem-cell-treatment#1
https://www.cancerresearchuk.org/about-cancer/cancer-in-general/treatment/bone-marrow-stem-cell-transplants

1. The stomach can hold a lot of food.

When empty, the stomach is pretty small – it is only about the size of your fist. However, it is also capable of stretching to hold up to 4 liters of food – equal to about 8 tubs of Ben & Jerry’s ice cream! This capacity to store food is important: we can eat much faster than we can digest food. It takes anywhere between 6 to 8 hours for food to pass through the stomach and into the intestine, and it can take up to 3 days for food to travel through the entire gastrointestinal tract.

2. The stomach has many different parts.

Although diagrams of the stomach might make it seem as though it is just a sack, it actually has different parts that perform various functions. The main part of the stomach, the body, is where food is churned and broken down. It is mixed with a cocktail of acidic gastric juices to form a semi-fluid gloopy mass called chyme. The fundus, which forms the upper portion of stomach, is where the air that enters the stomach when we swallow is stored and undigested food is retained before it is mixed in with chyme in the body of the stomach. The lowest part of the stomach is called the pylorus, and it connects the stomach to the small intestine. It prevents the contents of the intestine from rising back up into the stomach when the small intestine contracts.

3. The acid in our stomach is strong enough to digest most of the organs in the body. It is even strong enough to dissolve some metals!

The cells lining the wall of the upper regions of the stomach secrete hydrochloric acid, which has a pH between 1 and 2. For comparison, that is approximately the pH of the acid in car batteries, and is so acidic that it can dissolve steel. In the body, the hydrochloric acid starts to digest food and kills any microorganisms that might have entered the body along with the food. You might wonder how gastric acid doesn’t digest the stomach itself along with digesting the food it contains. After all, if the acid is strong enough to dissolve steel and cause severe chemical burns if skin were to touch it, the stomach could very well be harmed. The stomach is protected by mucosal cells that secrete a layer of mucus that protect the walls of the stomach. The mucus is 95% water and 5% polymers which give mucus its thick consistency. The mucus contains bicarbonate ions which neutralize some of the hydrochloric acid.

4. The stomach is the only organ in the digestive system that has three layers of muscles.

Unlike the walls of the rest of the organs in the digestive system, the wall of the stomach is comprised of three layers of muscles. The outer layer is made up of longitudinal muscles, the middle layer is made up of circular muscles, while the inner-most layer – called the oblique layer – has muscles that run diagonally. The outer two layers help in the movement of food down the stomach and into the small intestine, while the inner layer – the layer unique to the stomach –allows the stomach to churn the food and helps in physical digestion. These muscles are why we can digest food even if we are standing on our heads: it is the muscles that move food along the digestive tract, and not gravity!

5. The stomach is like a small chemical factory.

The stomach secretes a lot of chemicals. As mentioned above, it secretes hydrochloric acid that helps with digestion. It also secretes chemicals that stimulate the secretion of gastric acid. Additionally, it secretes a hormone called ghrelin. Ghrelin is often called the “hunger hormone” because ghrelin levels rise after fasting and make us want to eat!

Sources:

• https://open.oregonstate.education/aandp/chapter/23-4-the-stomach/

• https://www.mayoclinic.org/digestive-system/expert-answers/faq-20058340#:~:text=After%20you%20eat%2C%20it%20takes,move%20through%20the%20entire%20colon

If you’ve ever watched dramas such as Grey’s Anatomy, The Good Doctor, or House, you’ll definitely have heard these terms at least once: PET, CT, or MRI. Among the vast array of medical terminology, positron emission tomography (PET), computerized tomography (CT), and magnetic resonance imaging (MRI) scans are perhaps three of the most well-known. Whilst mentioned almost interchangeably, each member of this trio of imaging technology actually differs significantly from each other, but can also work in conjunction with each other. But what are the key differences?

To begin with, CT scans are composed of various X-ray images taken from different angles, generating a more holistic image of the patient’s bones, tumors and even cancers. CT scans are more precise and detailed than normal X-rays, but come with an added cost and radiation intensity. MRI scans, on the other hand, do not involve any form of radiation, instead relying upon a combination of magnetic force and radio waves to observe soft tissues and the nervous system. MRIs also generate images of bones, tumors, and cancers, but are superior to CT scans in terms of image quality and depth. However, this burdens the former with a heftier price tag and slower imaging process than the latter. If you need a more detailed image of your soft tissue, ligaments, or organs, your doctor will commonly suggest an MRI. If you need a general image of an area like your internal organs, or due to a fracture or head trauma, a CT scan is often recommended.

The third and newest form of imaging, the PET scan, differs from the other two imaging techniques due to its focus on imaging organs rather than bones. PET scans are often performed on CT/PET or MRI/PET combination machines, meaning they are used in conjunction with CT and MRI scans. During the procedure, patients are injected with a liquid containing small radioactive particles and sent through a PET scanner that picks up the particles in the organs. Compared to CT and MRI scans, PET scans take almost 10 times as long, require intense preparation and are considered an invasive procedure. They are significantly more expensive and leave trace amounts of radiation in the patient’s system, but are extremely useful in monitoring bodily functions and are more successful at detecting early-stage cancers. PETs yield images that are not as clear as CTs and MRIs, thus using them in conjunction with the latter two allows for an in-depth yet dynamic imaging treatment.

While the three different types of imaging technology have a number of similarities, their primary differences are in the areas of administration, procedure, and risk. While CT and MRI scans are commonly used on structures such as bones, their differences in cost and risk lead to gaps in imaging quality and efficiency. On the other hand, PET scans are used to monitor body functions and prove significantly more efficient at identifying cancers, despite their added risk. So, despite their similarities, none of these technologies can completely compensate for another and, like a lot of things in life, can be used together to strengthen their individual qualities, providing more comprehensive results and saving lives, one scan at a time.

When the word “symbiosis” comes up, people typically think of lichens – composite organisms established from fungi and algae. Or they think about clownfish and sea anemones – a relationship seared in our memories thanks to Finding Nemo. Humans, however, don’t come to mind. It turns out, however, that we are helped by millions of bacteria that live inside us. These bacteria are not only more numerous than we might guess, but also play roles extending beyond digestion. Here are some interesting facts about the gut microbiome:

1. The gut microbiome is enormous – there are upwards of 30 trillion bacterial and fungal cells in the gastrointestinal tract, most of which reside in the colon. This makes the number of microorganisms housed in the gastrointestinal tract equal to, if not slightly higher than, the number of cells that compose the human body itself!
2. While the number of human cells might just equal the number of cells constituting the gut microbiome, the number of genes encoded by the human genome is no match for the number of genes encoded by the gut microbiome. The gut microbiome encodes approximately 150 times the number of genes encoded by the human genome.
3. These extra genes come in handy to humans. These genes allow the bacteria to produce an array of enzymes that help humans digest complex carbohydrates in the large intestine and extract nutrients from them. In the absence of these enzymes, the human body would not have been able to get nutrients from a lot of the food we consume.
4. The gut microbiome also helps synthesize vitamins B and K in the body. Vitamin B plays an important role in metabolism, while vitamin K is required for blood clotting. The gut microbiome also helps the body absorb chemicals such as phytochemicals and polyphenols that function as antioxidants.
5. Our diet influences the composition of our microbiome. Those who consume a plant-based diet and those who consume a diet rich in animal-based-products have gut microbiomes that are enriched in different bacterial species. Consumption of foods rich in probiotics can also help alter the composition of the gut microbiome.
6. The gut microbiome plays an important role in modulating inflammation. Inflammation is a process by which the body stimulates the immune system by secreting chemical signals called cytokines. While this system is beneficial If the body is being invaded by pathogens, continuous inflammation leads to tissue damage. While some bacteria can protect against chronic inflammation by producing anti-inflammatory cytokines, some species can cause inflammation as well.
7. A disrupted microbiome – particularly a disruption in which there is an over-enrichment of microbes that cause inflammation – has been associated with numerous diseases including irritable bowel syndrome (IBS), inflammatory bowel disease (IBD), colorectal cancer, and type II diabetes. While it may seem difficult to believe that the microbes in the gut can play a role in notoriously complicated diseases like IBD, fecal transplants from healthy individuals that aim to rebalance the microbiome of a patient suffering from IBS or IBD have led to an alleviation of symptoms.
8. The gut microbiome can even regulate mood and memory – aspects of the functioning of the human body that don’t seem connected with the gut and digestion at all. In fact, the gut microbiome produces numerous neurotransmitters that regulate mood, including serotonin, the hormone that causes the feeling of well-being and happiness.

New research has only begun to elucidate the complex connection between the food we consume, the bacteria in the gut that help digest it, and the resultant effect on our long-term health. The interconnectedness between the bacteria in the gut and the chemical responses they stimulate in the body is evidence of the complex ways in which organisms depend on one another, and how the tiniest of organisms can have massive impacts on our health.

Sources:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4566439/

https://link.springer.com/article/10.1007/s10620-020-06109-5

https://link.springer.com/article/10.1007%2Fs00394-017-1445-8

https://www.thelancet.com/journals/ebiom/article/PIIS2352-3964(19)30800-X/fulltext

https://www.nature.com/articles/s41575-018-0061-2

https://link.springer.com/article/10.1007/s12328-017-0813-5

https://www.nature.com/articles/s41575-019-0209-8

https://www.thelancet.com/journals/ebiom/article/PIIS2352-3964(19)30639-5/fulltext

https://www.nature.com/articles/s41422-020-0332-7

https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.1002533

https://bionumbers.hms.harvard.edu/bionumber.aspx?s=n&v=1&id=113400

https://www.apa.org/monitor/2012/09/gut-feeling