More treatment is not always better. Cancer patients and their doctors often face difficult decisions about how much chemotherapy and/or radiotherapy is the best course for the individual. For colon cancer diagnosed at stage I, II, or III, surgery is the first line treatment. Adjuvant, meaning additional, treatment with chemotherapy is believed to be beneficial for stage III cancer, but not for stage I. For stage II, the use of chemotherapy is still a topic of debate.
Each individual is different, and the optimum treatment depends on many factors. Two research groups have developed computer models to predict the results of chemotherapy. Both are available online. The Numeracy calculator is provided by the Mayo Clinic, based on data from 3,302 patients from seven randomized trials. It has four inputs:
1. Lymph nodes (none, 1 – 4, or 5+)
2. Tumor stage (T1/T2, T3, or T4)
3. Grade (low or high)
4. Age (49 or younger, 50 – 59, 60 – 69, or 70+)
Thus, there are 72 different combinations. The Adjuvant! calculator is based on data from the U.S. Surveillance Epidemiology and End Results (SEER) tumor registry, and provides additional inputs:
1. Gender (male or female)
2. Comorbidity (perfect health, minor problems, average for age, or major problems)
3. Number of examined lymph nodes (0, 1 – 3, 4 – 10, >10)
The chemotherapy regimens are 5-FU (5-fluorouracil plus leucovorin) and FOLFOX ( 5-fluorouracil plus leucovorin plus oxaliplatin).
Researchers at Johns Hopkins University, the Mayo Clinic, Creighton University in Nebraska, and the University of British Columbia performed a comparison of these two calculators. They chose 192 hypothetical patient scenarios, using characteristics of individuals who could be chemotherapy candidates. The results indicated small but statistically significant differences between the two calculators.
Thus, when you see small differences between survival rates with different treatment options, it is important to understand that these could be numerical artifacts. Both websites encourage users to have a health care provider help with entering data and interpreting results, since the patient may not be as familiar with all the input options. However, I think the Numeracy calculator appears fairly simple for the average user. Reference 1 suggested that both calculators can give better predictions than a clinician estimate without such resources.
References:
1. Bardia A et al, “Adjuvant chemotherapy for resected stage II and III colon cancer: Comparison of two widely used prognostic calculators”, Semin Oncol. 2010 Feb; 37(1): 39-46.
2. The Numeracy calculator online:
http://www.mayoclinic.com/calcs/
3. The Adjuvant! calculator online:
http://adjuvantonline.com/index.jsp
Linda Fugate is a scientist and writer in Austin, Texas. She has a Ph.D. in Physics and an M.S. in Macromolecular Science and Engineering. Her background includes academic and industrial research in materials science. She currently writes song lyrics and health articles.