Breast Cancer - Case Notes

SCI Home | SCI Faculty Page | Cover Sheet | Reference List | Users Notes

Author - Rachelle Spell - Summer 1997

Teaching Notes This case may take one or two weeks. Incorporating reading assignments from Ziman will lengthen the case. Proposed syllabus:

First day: Read the first handout of newspaper articles in class and discuss questions 1 and 2. I suggest playing the devil’s advocate so that the students must defend "science".

Question 1. Is this a important health topic? Would you think from reading these articles that breast cancer is the most common cause of death in women in the U.S.? This question should bring up discussion of how and why science (admittedly medical science) affects our lives, how we are expected to absorb and interpret science, and the difficulties involved in that interpretation. Although a serious disease, breast cancer is the fourth most common cause of death, after heart disease, stroke, and lung cancer. Somehow, these articles offer a more sensationalized picture.

Question 2. a. Based on the information in the last article, calculate how many females get breast cancer each year (total U.S. population =250 million)? This question should offer a little reality check, a test of number literacy, and a discussion of the incompleteness of the reported information:
175,000 cases every year/ 125,000,000 women in the U.S.
= 175,000/125,000,000=0.0014= 1/700 women One in 700 females gets breast cancer every year.

b. How does your calculation compare with the 1 in 9 estimation? What does 1 in 9 mean, exactly? The risk of a woman developing breast cancer during her lifetime is 1 in 9. Though not discussed in this article, that level of risk is not reached until the woman is in her 80’s. That is, the risk is much lower than 1 in 9 until a woman turns 85 years old. But if a woman lives until 85, she has had a 1 in 9 chance of developing breast cancer. (More recent data indicate the risk is 1 in 8.)

c. What is your current risk of developing breast cancer? The information needed to relate these numbers to college age women is not presented in this article, but will be presented later.

Discussion: Does the article adequately discuss the relevance of such data to the readers? Is the information in the article useful for the average reader? Or is it written to scare the newspaper’s readers so that they will buy more newspapers? Why do newspapers report on science/medicine? Is this science? What is science? (This line of discussion should lead naturally into the next question.)

Second day: Assigned reading and homework: Ziman Chapter 1 with respect to the discussion on the first day and write out answers to question 3 at the end of the first handout. The students are to use the breast cancer discussion to get at the question what is science.

Question 3. Based on the excerpts given here, how do you decide which article to believe? Why do you believe any of them? Why do you believe in science? What is science? Possible answers to the question how does one decide which article to believe:

• so complicated that it must be true
• most recent
• from the most prestigious research center
• by the most famous doctor
• associated with an esteemed organization (e.g. the American Cancer Society)
• sounds sensible

All but the first have at least some truth to them. I would use this chance to discuss the specifics of modern science, heading toward a more general discussion of the abstract epistemology of science. - Science often evolves in small increments (two steps forward, one step back).

• "90% of the information in textbooks is true, 90% in journals is false." (Ziman 2.10)
• Researchers of exceptional ability are more likely to be famous and be at "well-known" research centers than mediocre scientists.
• If information is accepted by an esteemed organization that implies that many capable scientists there have considered the data and found it credible.

All of the generalizations listed here can be used to make the terms consensible and consensual more understandable. (Ziman 1.4):

• The small increments of the evolution of science are consensible but not necessarily consensual.
• Peer-reviewed journal articles are generally consensible. Textbooks are generally consensual. - Good scientists generate consensible information; "great" scientists generate consensual information.
• Acceptance by a large group of scientists (e.g. at the American Cancer Society) indicates consensibility.

What is science? (Ziman 1.2 p.2-3) "I have tried to show that scientific knowledge is the product of a collective human enterprise to which scientists make individual contributions which are purified and extended by mutual criticism and intellectual cooperation."

Is this science? Yes, but this is science filtered down to us by the media. The media wishes to inform you in such a way that you are compelled to continue buying their newspapers to stay "informed". To better understand what is science, let us read an original report by the American Cancer Society and an original article from a peer-reviewed journal.

Question 4. How do scientists know what to believe? What do scientists in general need to do science? What is science? (Ziman 1.2 p.2-3) "I have tried to show that scientific knowledge is the product of a collective human enterprise to which scientists make individual contributions which are purified and extended by mutual criticism and intellectual cooperation."

To do science, to reach consensibility, scientists require unambiguous communication (Ziman 2.1), a model system/framework (Ziman 2.5), a falsifiable prediction (Ziman 2.8 and 2.9), and a controlled experimental environment (Ziman 3.3 and 7.4). To attempt to reach consensuality, scientists must submit their work to peer review and publish (Ziman 6.3)

Third day: Assigned reading and homework: Ziman Chapter 2 with respect to the discussion on the first day and write out answers to question 4 at the end of the first handout. The students are to use the breast cancer discussion to get at the question how science is done.

Fourth day: Assigned reading: American Cancer Society Information and original journal article (to be picked from the reference list). Discuss in class the scientific methods involved in those studies and the structure of the scientific article. Attempt to teach them how to read critically. Just as students must learn to read literature critically, they should learn how to read scientific literature critically. Get the students to practice using precise language in preparation for their next assignment.

Relate the information in the ACS handout to the conclusions the students made about breast cancer risks on the first day of the case study. Do they think the information in the newspaper articles was misleading? Where do the students think the information in the ACS handout came from?

The references from the ACS site are here so that the teacher may choose the journal article for the students to use or so that the student may choose which article to use. I have included two clearly written, short articles. More recent articles not listed here may also be chosen. Allowing the students to choose the article of most interest to them may make the experience more rewarding for them but will complicate the discussion and critique on the last day in class.

Questions for the discussion of the journal article:

• The article structure: abstract, introduction, materials and methods, results with information organized into charts or figures, discussion, and references. This structure standardizes how information is relayed.
• unambiguous communication: this could be equations, numbers, graphs, or pictures
• The hypothesis: falsifiable, testable, predictive. Ask the students what the researchers want to test.
• the experiment: controlled, repeatable. Ask the students if the results truly answer the proposed question.
• References: All information must have a reference. This exercise can indicate which piece of background information is actually an assumption.

Of course, this list is not exhaustive, but I hope it is helpful. Expertise in the area is not necessary. I think the students will appreciate if the professor works through the article with them. The students may have questions we are not able to answer. If so, show them how you could use the references to track down the information needed.

Fifth day: Homework assignment: The students write their own newspaper story (about 500 words) incorporating the information in the ACS Handout and the journal article in an effort to produce an article informative to the general public. In class, the students will read each other’s article in groups and discuss the information with respect to consensibility/consensuality.