GU cancer

Aussies at ASCO: Prof Linda Mileshkin on the practice-changing OUTBACK trial results in advanced cervical cancer

Wednesday, 9 Jun 2021

Prof Linda Mileshkin

Standard therapy using chemoradiation alone remains the best current treatment for women with locally advanced cervical cancer, according to Australian researchers presenting at the ASCO 2021 virtual meeting.

Professor Linda Mileshkin from Peter Mac reported long-anticipated findings from the OUTBACK trial showing that the addition of adjuvant chemotherapy given after standard therapy does not improve survival outcomes. What’s more, the strategy is associated with additional severe side effects.

The five year findings are likely to immediately change practice for early adopters of the strategy who had hoped the regimen would reduce distant disease recurrence after a large meta analysis and subsequent smaller studies supported it’s use.

However, until now, there has been no evidence from a large phase III study for or against the addition of chemotherapy in this setting – an evidence gap that OUTBACK set out to close.

The phase III international trial enrolled 919 patients with locally advanced cervical cancer. Patients were randomly assigned to receive standard cisplatin-based chemoradiation with or without additional chemotherapy with carboplatin and paclitaxel.

Addressing the plenary Professor Mileshkin said the study confirms that chemoradiotherapy alone is currently the best treatment  for women with locally advanced cervical cancer.

“Not only is there no benefit with adjuvant chemotherapy, but severe side effects are also increased,”she added.

At five years, overall survival (OS) was comparable for both groups – 72% v. 71%, respectively, for those receiving the additional adjuvant chemotherapy and those receiving standard care.  

Disease had not returned for 63% of patients who received additional chemotherapy, compared with 61% who received chemoradiation alone. Patterns of disease recurrence were similar in the two treatment groups.

More serious adverse events (grade 3-5) were experienced by 81% of patients who received additional chemotherapy, versus 62% in the standard treatment group up to 1 year following randomisation.

“The established toxicities of carboplatin and paclitaxel, such as haematolgoic toxicity, alopecia, fatigue, myalgia and neuropathy were seen at significantly high rates in the adjuvant chemotherapy,” says Professor Mileshkin noting that expected gastrointestinal toxicities from chemotherapy such as nausea and vomiting were also significantly increased in the adjuvant chemotherapy arm. Febrile neutropenia rates however were low being 2% in both arms.

Meanwhile global health and quality of life scores were impaired during and shortly after chemotherapy among participants in the adjuvant theory arm but were similar between the groups  from months 12 to 36, she also noted.

In a press release accompanying announcement of the late breaking presentation ASCO president Professor Lori Pierce said the study confirms that the current standard treatment is the best possible at this time and signals a change of practice for early adopters of the additional therapy.

“This trial provides clear evidence that the addition of chemotherapy after chemoradiation does not extend survival. The results are immediately practice-changing, showing that this approach should not be used to treat locally advanced cervical cancer. We can now spare our patients the side effects and toxicity that comes with additional chemotherapy.”

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