Chemotherapy Break Linked to Worse Outcomes for Advanced-Stage HER2-Negative Breast Cancer

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A schedule of continuous chemotherapy for women diagnosed with advanced-stage HER2-negative breast cancer offered better overall survival and progression-free survival than a schedule with breaks from chemotherapy, according to a study.

A separate analysis of the same study found that quality of life was about the same no matter which chemotherapy schedule the women were following.

The research:

was presented on May 3, 2019, at the 2019 European Society for Medical Oncology Breast Cancer Congress in Berlin.

Overall survival is how long the women lived, whether or not the cancer grew. Progression-free survival is how long the women lived without the cancer growing.

Advanced-stage breast cancer is either locally advanced breast cancer or metastatic breast cancer. Locally advanced breast cancer is breast cancer that has spread to tissue near the breast, but not to parts of the body away from the breast. Metastatic breast cancer is cancer that has spread to parts of the body away from the breast, such as the bones or liver.

Stop and Go trial survival outcomes

This study, called the Stop and Go trial, looked at the safety, effectiveness, and quality of life outcomes of a continuous chemotherapy schedule vs. a schedule with a break from chemotherapy for women diagnosed with advanced-stage HER2-negative breast cancer. The study looked at results from two lines of chemotherapy treatment.

For the first line of chemotherapy treatment, 420 women were treated with Taxol (chemical name: paclitaxel) and Avastin (chemical name: bevacizumab). The women were randomly assigned to receive chemotherapy on one of two schedules:

  • four chemotherapy cycles, a break, then four more cycles, called intermittent chemotherapy
  • eight chemotherapy cycles with no break, called continuous chemotherapy

After completing the first line of chemotherapy, 270 of the women completed a second line of chemotherapy of either Xeloda (chemical name: capecitabine) or Myocet (chemical name: non-pegylated liposomal doxorubicin). The women were again randomly assigned to one of two chemotherapy schedules:

  • 131 women were on the intermittent chemotherapy schedule
  • 139 women were on the continuous chemotherapy schedule

Looking at all 420 women in the study, overall survival was:

  • 20.9 months for women on continuous chemotherapy
  • 17.1 months for women on intermittent chemotherapy

Progression-free survival was:

  • 13.9 months for women on continuous chemotherapy
  • 12.7 months for women on intermittent chemotherapy

The researchers also looked at overall survival and progression-free survival for just the 270 women who completed the second line of chemotherapy, looking at outcomes for the first and second line of chemotherapy combined, as well as outcomes for just the second line of chemotherapy.

Overall survival for the two lines of chemotherapy combined was:

  • 23.0 months for women on continuous chemotherapy
  • 20.3 months for women on intermittent chemotherapy

Progression-free survival for the two lines of chemotherapy combined was:

  • 16.6 months for women on continuous chemotherapy
  • 14.6 months for women on intermittent chemotherapy

Overall survival for just the second line of chemotherapy was:

  • 12.0 months for women on continuous chemotherapy
  • 10.6 months for women on intermittent chemotherapy

Progression-free survival for just the second line of chemotherapy was:

  • 5.0 months for women on continuous chemotherapy
  • 3.5 months for women on intermittent chemotherapy

“Our main focus in this analysis was on the efficacy of second-line treatment, although, interestingly, the updated overall survival results showed that for the whole population (those who received first line only, or first and second lines of treatment) the survival was better with continuous treatment as well,” lead author Frans Erdkamp, M.D., of the Zuyderland Medical Center, said in a statement.

Stop and Go trial quality of life outcomes

Many doctors believe that taking a break from treatment can help improve quality of life. To investigate this idea, the researchers sent the women in the Stop and Go trial a survey every 12 weeks. The survey was a standard tool used to measure quality of life.

“In clinical practice, we see considerable variation in treatment strategies, so [we] felt it would be helpful to conduct a trial investigating the effect on quality of life of scheduling with modern agents,” lead author Anouk Claessens, M.D., also of the Zuyderland Medical Center, said in a statement. She said the researchers hypothesized that treatment holidays incorporated into scheduling would benefit quality of life.

A total of 398 women completed the surveys.

There was little difference in quality of life scores for the women on a continuous chemotherapy schedule compared to the women on an intermittent chemotherapy schedule.

“We were a little surprised at the findings running contrary to our hypothesis,” coauthor Monique Bos, M.D., of Erasmus University Medical Center, said in a statement. “In explaining therapy schedules to patients, we tend to suggest that a 'holiday,' by nature of the word, might be beneficial, but this was not the case.”

“Both studies confirm the current national and international guidelines that chemotherapy, preferentially monotherapy — at least after first line, should be given continuously, as long as it is well tolerated and effective,” Nadia Harbeck, M.D., of the University of Munich, who was not involved in the Stop and Go trial, said in a statement. “Until now, we’ve only had evidence from older studies, with regimens no longer used, indicating that continuous chemotherapy in metastatic disease is better than shorter. The new Stop and Go data confirm these older data also with more modern regimens.

“The result that continuous chemotherapy is not at all associated with worse quality of life is clinically meaningful,” Harbeck continued, “and further highlights the importance of preferring to administer chemotherapy continuously for benefitting the most our patients with advanced disease.”

What this means for you

If you’ve been diagnosed with advanced-stage HER2-negative breast cancer, you and your doctor will discuss a number of treatment options. This study suggests that continuous chemotherapy may offer better outcomes than taking a break from chemotherapy, with similar quality of life.

Still, if you are struggling with side effects, a treatment break may be the right thing for your unique situation.

Together, you and your doctor will decide on the best treatment plan for you.

Written by: Jamie DePolo, senior editor


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