Breast cancer: Rethinking the merits of chemotherapy

February 3, 2003

Some breast cancer patients may not benefit from chemotherapy

 

HOSPITAL PRACTICE

Breast cancer:
Rethinking the merits of chemotherapy

Few things strike terror in a patient as much as hearing the words, Youhave breast cancer. Not only is the diagnosis frightening, but thetherapies used to treat the disease are just as daunting-surgical removal ofbreast tissue; radiation; and, of course, chemotherapy. Although most sideeffects associated with chemotherapy are temporary in nature-such as nausea andhair loss-other adverse effects such as heart damage, secondary cancers, andcentral nervous system effects of memory loss and sensory/motor neuropathiesmay cause long-term problems.

Fortunately, as we learn more about the disease, data suggest that maybe notevery woman with breast cancer really needs chemotherapy. The reason? Dependingupon patient-specific variables, chemotherapy may not offer much in the way oflong-term survival benefits over hormonal therapies such as antiestrogens,aromatase inhibitors, or even ovarian ablation.

While the average patient with breast cancer believes chemotherapy willimprove the efficacy of cancer treatment by 80%-90%, the truth is thatchemotherapy improves long-term survival by only 10%-30% for most women withbreast cancer. For many women, the potential benefits of chemotherapy may notoutweigh the risks associated with treatment.

According to Jim Koeller, Pharm.D., professor at the College of Pharmacy,University of Texas Health Science Center, women with advanced stages of breastcancer are unquestionably candidates for chemotherapy treatment. On the otherhand, women with stage 0/1 disease may not derive much added benefit fromchemotherapy-especially in light of the risks inherent to the treatment itself.

Therefore, Koeller pointed out, "The question arises, at what point doyou offer patients chemotherapy? The data support that there are people we canwatch, since the majority of breast cancers are now being detected at earlierstages."

Thanks to early detection, most women with breast cancer are identified atstage 0/1; these individuals have less than a 20% risk of developing systemicdisease. In fact, according to Peter Ravdin, M.D., Ph.D., oncologist atUniversity of Texas Health Science Center, "In some women, the risk ofdeveloping systemic disease is actually closer to only 5%."

Of course, there are many variables that ultimately determine each woman'sindividual risk of developing invasive disease from breast cancer metastases.Risk of systemic disease depends upon numerous variables-the size of the tumorwhen detected, the number of lymph nodes affected, a woman's pre- orpostmenopausal status, and whether the tumor is hormonally sensitive toestrogen.

As a result of new data emerging from analyses like the Oxford Overview ofthe Early Breast Cancer Trialists' Collaborative Group, which evaluated 190,000women with breast cancer from 290 different clinical trials, the overallsurvival benefits of chemotherapy have been assessed. Using this evidence-baseddata, predictions can be made about the net benefit chemotherapy will offerbreast cancer patients based upon each specific situation. To assist inassessing appropriate breast cancer treatments, Ravdin has developed acomputer-based tool called Adjuvant! in which healthcare professionals"plug in" specific variables for each patient with breast cancer. Inresponse to data input, Adjuvant! predicts the net benefit of chemotherapy interms of 10-year survival rates.

Many postmenopausal women with estrogen-receptor positive breast cancercaught at early stages are surprised to find that the net benefit ofchemotherapy at 10 years is often less than 1%-when chemotherapy is added tohormonal therapies. Considering that there is a 0.5% chance of achemotherapy-related death (due to infection, heart disease, secondary cancer,etc.) during the same 10-year period, some women opt to forgo chemo because ofthe relatively small benefit when compared with risks.

Said Ravdin, "Adjuvant! is a powerful tool because it challengesphysicians to think about adjuvant regimens and it facilitates discussion toengage patients in making a decision."

As a result of all the information that is so readily available, physiciansand patients alike are proceeding with therapeutic decisions better informedthan ever before. And, increasingly, women diagnosed in early stages of breastcancer-once armed with the facts-are deciding that chemotherapy is not always anecessary part of their treatment regimen.

Kelly Dowhower Karpa, Ph.D., R.Ph.

The author is a clinical writer based in the Philadelphia area.

Key features of Adjuvant!

  • Estimates baseline prognosis for individual patients

  • Estimates efficacy of chemotherapy and hormonal regimens

  • Contains "help" files that explain criteria used to make calculations (if a clinician disagrees with assumptions, he may "plug in" his own values)

  • Provides regimen-specific toxicity sheets for patients

  • Conveys information to patients in a useful format

 



Kelly Karpa. Breast cancer: Rethinking the merits of chemotherapy.

Drug Topics

2003;3:29.