Study: Nearly half of breast cancer patients experience a severe side effect after treatment

IN DEPTH REVIEW OF RESEARCH

Study background:

Health care providers always take care to ensure that a treatment is greater than its potential risks, but treatment can be more difficult with drugs such as cancer treatments where the dose needed often causes side effects.

While information is available regarding treatment side effects from clinical trial studies and health care claims, few studies have thoroughly examined the side effects that breast cancer patients experience after treatment outside of those settings. Additionally, participants of these studies are typically patients with late-stage breast cancer. Christopher Friese and colleagues from the University of Michigan School of Nursing and other institutions published research in 2017 in the journal Cancer that studied the side effects of women who were treated for their early-stage breast cancer.

Researchers of this study wanted to know:

What are the side effects, severity of those side effects, and patient burden associated with treatment for early-stage (I or II) invasive breast cancer?   

Population(s) looked at in the study:

This study used data from 1,884 women, ages 20-79, with early-stage (I or II) invasive breast cancer of any type.  Women who had stage III or IV cancer or tumors bigger than 5 cm were excluded. The data was taken from the Los Angeles County and Georgia Surveillance, Epidemiology, and End Results (SEER) programs. Among the participants, 1,057 women were white, 321 were black, 315 were Latina, 141 were Asian and 50 were of unknown race or ethnicity. The patients received primary breast surgery (lumpectomy, unilateral or bilateral mastectomy) and may or may not have had radiation, chemotherapy, or both radiation and chemotherapy.

The researchers mailed surveys about two months after each woman’s surgery, asking patients to rank the severity of their side effects, including nausea/vomiting, diarrhea, constipation, pain, arm swelling, difficulty breathing, and breast skin irritation. Patients were also asked to fill out a survey about their physical health (the PROMIS measure) and health care services they used because of side effects.  This allowed the researchers to measure the patient burden of side effects after treatment.

Study findings: 

1. 45% of breast cancer patients reported that they experienced at least one “severe” or “very severe” side effect after treatment.
2. Factors associated with a more severe side effect were:
   • Receiving chemotherapy alone or in combination with radiation
   • Latina ethnicity
3. An association was observed between patients’ PROMIS score (measure of physical health) and side effects experienced. Patients who did not experience side effects had higher PROMIS scores, indicating better physical health, while patients who did experience side effects had lower PROMIS scores, indicating worse physical health.
4. 9% of women reported unscheduled visits to their health care providers to manage their side effects; 5% of women visited an emergency department or hospital for their side effects.

Limitations:

This study was conducted through patient surveys; researchers did not have access to patients’ health records.  Studies such as these that rely solely on patients’ memories can include errors due to patients’ recall (for example, not remembering a side effect experienced or remembering it as more or less severe than it would be classified by a health care provider). Additionally, while the researchers recruited a fairly diverse group of women, because the study was limited to two geographic regions (Los Angeles and Georgia), the study conclusions may not be applicable to other areas. Finally, this study only included women with early-stage breast cancer; most had ER+/HER2- tumors. Additional work is needed to examine the effect in more advanced breast cancers. The researchers’ analysis did not separate early-stage breast cancers into different subtypes—depending on a patient’s subtype, individuals may have received different treatments compared to other patients, so the results may not be widely applicable to all patients.

Conclusions:

This study suggests that almost half of women with early-stage invasive breast cancer experience at least one severe or very severe side effect after treatment. The study authors identified many clinical implications from this study, writing: “The toxicity burden faced by patients may be greater than acknowledged by clinicians, and warrants routine assessment during and between clinical visits. Differential toxicity patterns identified in this diverse, population-based sample of women may help clinicians when they review the risks and benefits of breast cancer treatment options.”

Posted 4/11/17

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