Radiation and Chemotherapy: Treatment or Cause?

The article, “How Cancer Shapes Evolution and How Evolution Shapes Cancer” explains cancer and cancer treatment from an evolutionary perspective. One topic of the article states that receiving cancer treatment through radiation or chemotherapy can actually worsen the cancer or allow a second cancer to develop. This is because “Although cytotoxic treatment can initially cause a major reduction of the tumor size, this also creates powerful pressure that will frequently select for clones that have intrinsic resistance to the regimen. This evolutionary ability of the tumor cells
thus results in regimen failure and regrowth of the cancer, populated by resistant cells” (Casás-Selves et al p. 6). As this quote explains, cancer treatment often only kills the least dangerous cancerous cells (the ones with the least resistance) and allows the better adapted clones to remain and grow more resistant.

Scientists are the University of California, San Diego, discovered an explanation for how this resistance occurs. Journalist Jamie Reno explains their findings saying, “Researchers found that two of the drugs — Erlotinib for lung cancer and Lapatinib for breast cancer — are effective for a while, but eventually stop killing cancer cells and begin prompting them to resist the drug and become more aggressive” (p.1). At this stage of resistance, treatment actually contributes to tumor growth due to a molecule called CD61. Researchers found that cancer treatment can cause this molecule to rise to the surface of the tumor and “spur tumor cells to acquire more stubborn, stem-cell-like properties, including an ability to survive almost anywhere in the body” (Reno p.1). 

Because treatment can increase the ability of cancer cells to survive throughout the body, secondary cancers can occur. These are cancer growths that can appear anywhere in the body and have three characteristics: “1) histologic features of first cancer and secondary cancer are different, 2) secondary cancer is within the area previously treated with radiation, and 3) the secondary cancer has a latency period of 5 years – that is, the secondary cancer develops five years or later after the first” (Loiselle p. 1). 

The idea that the means of treatment for cancer can either worsen the current cancer or cause a second type to develop is incredibly frightening. Fortunately, there is a potential solution on the horizon: a drug called Bortezomib. This drug “is introduced to the drug-resistant tumors treated by an RTK [chemotherapy] drug, it reverses stem-cell-like properties of the tumors and re-sensitizes the tumors to drugs that the cancer cells had developed resistance to” (Reno p. 1). These drugs are still going through clinical trials, but are appearing to be a promising addition to the current therapies that are used for cancer treatment. One of the researchers performing these clinical trials reports that in mice, “he has seen no recurrence of lung, breast or pancreatic cancer activity once the second drug is added” (Reno p. 1). In order to maximize the effectiveness of this process, oncologists plan to monitor patients drug resistance early in the treatment process and administer Bortezomib as early as resistance is detected (Reno p. 1).

Cancer treatment is still a new and highly imperfect process. Not only are current methods unreliable, but they can also make the cancer worse or cause it to reoccur. Fortunately, new drugs are being developed that can potentially help counteract the dangers of current treatments. If these new drugs are approved, there may be greater hope for cancer remission.

1. Casás-Selves, M., & DeGregori, J. (2011, December 2). How Cancer Shapes Evolution and How Evolution Shapes Cancer. . Retrieved April 23, 2014, from https://ctools.umich.edu/access/content/group/dd756836-7171-480e-b38d-66e2fc80511c/Readings/CasasSelves_DeGregori2011EvoEduOutreach.pdf

2. Reno, J. (2014, April 20). New Cancer Drugs Make Tumors Drug Resistant, More Aggressive. International Business Times. Retrieved April 22, 2013, from http://www.ibtimes.com/disturbing-discovery-new-generation-targeted-cancer-drugs-cause-tumors-become-drug-1573800

3. Loiselle, D. (2011, May 9). Secondary Malignancies After Radiation Therapy. Global Resource for Advancing Cancer Education. Retrieved April 22, 2014, from http://cancergrace.org/radiation/2011/05/09/secondary-malignancies/

 

 

 

The Lobbying Debate over the Agricultural Use of Antibiotics

Antibiotic resistance is becoming a major issue throughout the world. Many people consider overuse of antibiotics by humans the main cause of this growing resistance. Unfortunately, it is not this simple. Even people who avoid taking antibiotics for their own treatment are at risk of developing an antibiotic resistant infection. How could this be? The answer is found in our food: our meat and even our produce.

When animals are being raised on farms for food production, they are fed high doses of antibiotics, which promotes growth and prevents epidemics among them. By regularly giving food-producing animals these antibiotics, we are at risk of ingesting antibiotic resistant bacteria. Even eating fruits and vegetables is dangerous, because typically these foods are grown in manure that comes from animals who were fed antibiotics.

Obviously, this problem needs to be addressed, particularly by the Food and Drug Administration (FDA); However, little action has been taken thus far. A recent report done by the John Hopkins Center for Livable Future found that the main reason for this lack of progress is due to opposition from the farming industry. The report explained that, “The Center for Responsive Politics data, combined with the most recent lobbying filings, show that The American Farm Bureau, the large nonprofit representing the interests of the farm industry, has spent more than $3.3 million on lobbying in the first three quarters of 2013, partly to advocate for the use of antibiotics” (Conradis 2013). Lobbies such as The American Farm Bureau are pouring mass amounts of funding into lobbying against restraints on antibiotic use on animals. Because the government depends on support from these large, moneymaking interest groups, they are reluctant to pass legislation against antibiotic use. In an interview with Yale Environment 360, Robert Martin explained that the Obama administration began taking strides to combat the problem but “because of pressure from the industry, they [the Obama administration] abandoned that effort late last year before the election. Every [presidential candidate] gets so focused on winning Iowa and Ohio and Minnesota — states that are heavy CAFO states — that they abandoned that effort to inventory operations” (Yale Environment 360 2013).

Although the lack of progress is discouraging, there is a potential for change. As Martin stated, “In the last five years, Rep. Louise Slaughter of New York has sponsored the Preservation of Antibiotics for Medical Treatment Act (PAMTA), which would ban for use in animal agriculture the top seven antibiotics important in human medicine” (Yale Environment 360 2013). In addition, this bill would require that medicines be used for therapeutic [not growth] purposes only and be approved by the Secretary of Health and Human Services before use on animals. In general, the PAMTA would place restrictions on antibiotic use for food producing animals by regulating them with specific guidelines. (Library of Congress Summary 2013). These restrictions would decrease the likelihood of humans obtaining antibiotic resistant bacteria from food.

Unfortunately, the bill proposed by Slaughter has very little support thus far, yet antibiotic resistance continues to be a growing problem throughout the world. One of the steps to combatting this issue, is if Congress enacts restrictions on antibiotic use in agriculture. There is potential that as public concern heightens and puts more pressure on politicians, legislation could be passed. Until then, we wait and eat carefully.

(1) Conradis, B. (2013, October 25). News & Analysis. Farm and Pharmaceutical Lobbies Push Back Against Antibiotics Legislation. Retrieved April 16, 2014, from http://www.opensecrets.org/news/2013/10/farm-and-pharmaceutical-lobbies-pus.html

(2) Henneberger, M. (2013, October 22). Report: Feeding antibiotics to livestock is bad for humans, but Congress won’t stop it. Washington Post. Retrieved April 16, 2014, from http://www.washingtonpost.com/politics/feeding-antibiotics-to-cows-is-bad-for-humans-but-congress-wont-stop-it-new-report-says/2013/10/22/ecd2de08-3afd-11e3-a94f-b58017bfee6c_story_1.html

(3) Russo, C. (2013, November 19). How Industrial Agriculture Has Thwarted Factory Farm Reforms. Yale Environment 360. Retrieved April 16, 2014, from http://e360.yale.edu/feature/interview_robert_martin_how_big_agriculture_has_thwarted_factory_farm_reforms/2712/

(4) Library of Congress. (2013, March 13). GovTrack. Retrieved April 16, 2014, from https://www.govtrack.us/congress/bills/113/hr1150#summary/libraryofcongress

 

The Effects of Birthing Method on the Development of the Microbiota

The importance of microbiota, defined as the community of microbes found in the human body (Pollan p. 2), was overlooked by scientists until recently; However, correlations between the increasing hygiene of the Western world and the increase in chronic diseases such as asthma, have caused scientists to reexamine this community of bacteria. Research now suggests that certain bacteria in the microbiota are essential to human health. As support for this theory increases, researchers have begun to examine the factors influencing the development of the microbiota.

Although research about this development is still a work in progress, there is considerable evidence suggesting that the method of delivery during birth influences the health of the microbiota. In his article, Some of my Best Friends Are Germs, Pollan explains that “most of the microbes that make up a baby’s gut community are acquired during birth — a microbially rich and messy process that exposes the baby to a whole suite of maternal microbes” (p. 4). Unfortunately, all births are not created equally. Caesarean births, which are significantly more sterile than vaginal births, do not allow infants exposure to the same level of bacteria that a vaginal birth would. This explains the higher rates of disorders such as asthma and allergies among C-section babies. Pollan explains that, “not having been seeded with the optimal assortment of microbes at birth, their immune systems may fail to develop properly” (p. 4). Thus, babies born by Cesarean are thought to start life without a fully developed microbiota.

In their primary article, Dominguez-Bello et al put this theory to the test by using gene pyrosequencing to characterize bacterial communities of mothers and their babies. Their research found that the bacteria found in babies were reflective of the bacteria they were exposed to during birth. The article explains that “Vaginally delivered infants harbored bacterial communities (in all body habitats) that were most similar in composition to the vaginal communities of the mothers” whereas “infants delivered via C-section harbored bacterial communities (across all body habitats) that were most similar to the skin communities of the mothers” (Dominguez-Bello et al p. 2). Specifically, samples from vaginally delivered babies had high levels of lactobacillus, prevotella, atopobium, and sneathia spp, four bacteria frequently found in vaginas. In contrast, babies born through C-section had high levels of Staphylococcus spp., a bacteria commonly found on the skin of mothers. These results demonstrate the influence that the birthing method has on the development of the microbiota.

This graph shows how the microbiota of babies is largely a reflection of their method of birth. Vaginally delivered babies have microbiota that resembles the community of bacteria found in their mother’s vagina. Babies born through C-section have microbiota that resembles the community of bacteria found on their mother’s skin. (Source: Dominguez-Bello et al)

In addition, the research by Dominguez-Bello et al showed that “in three of four vaginal deliveries, the mother’s vaginal bacterial community was significantly more similar to her own baby’s microbiota than to the microbiota of other vaginally delivered babies” (p. 2). This suggests that the development of microbiota is affected not only by the method of delivery, but also by the characteristics of the mother. The same is not true for babies delivered via Cesarean, as mothers of C-section babies “were no more similar to their own babies than to the other babies born via C-section” (p. 2). This difference may be due to other skin-level factors, such as the touch of a doctor, that infants are exposed to in the hospital. This lack of resemblance conveys the inability of C-section mothers to transfer microbes during birth.

Overall, the scientists found that “the mother’s vaginal microbiota provides a natural first microbial exposure to newborn body habitats” (Dominguez-Bello et al p. 2 ). Infants who are not born vaginally do not encounter this natural exposure. This lack of exposure may cause long-term issues for the infant, whose bacterial colonization is delayed (Dominguez-Bello et al p. 2). Due to the lack of optimal colonization, Cesarean-born babies are more prone to develop illnesses or disorders.

Unfortunately, Cesarean births are necessary in many cases. Because of this, the question becomes: how do we improve the microbiota of babies born via C-section? Although there may not be a way as effective as coming through the vaginal canal, there are some promising alternatives. One natural option is breastfeeding. As Dominguez-Bello et al explain “breastfeeding has been suggested to enrich vaginally acquired lactic acid-producing bacteria in the baby’s intestine” (p. 2). Breast milk is considered a probiotic, meaning in introduces new microbes into the body (Pollan p. 4). Another way to improve the microbiota of infants is to give them probiotics in the form of pills for a period of time. These alternatives may allow mothers who are forced to deliver via Cesarean to feel at peace about their babies’ health. Future research will be necessary to determine if these alternatives can compare to the effectiveness of vaginal birth in developing the microbiota.

Because fetuses are thought to develop in a bacteria-free environment, their exposure to bacteria begins upon delivery. This exposure differs based on the method of birth. Research suggests that Cesarean-born babies are not exposed to the same quantity and quality of positive bacteria as vaginally delivered babies are. Dominguez-Bello et al convey this theory in their research by analyzing the microbiota of babies as compared to their mothers. They found that babies born vaginally have high levels of the bacteria that is commonly found in a woman’s vagina and is specific to their mothers. In contrast, C-section babies have high quantities of skin-level bacterias that are not specific to their mothers. The lack of microbe diversity in Cesarean-born babies may explain their increased susceptibility to sickness and disorders.

Sources:
Dominguez-Bello et al http://www.pnas.org/content/107/26/11971.abstract
Pollan http://www.nytimes.com/2013/05/19/magazine/say-hello-to-the-100-trillion-bacteria-that-make-up-your-microbiome.html?pagewanted=all&_r=0