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CHICAGO -- A minimally invasive approach for operable pancreatic cancer proved safe and just as effective in terms of radical resection rates as open surgery, findings from the international showed.

For the study's primary endpoint, 73% of patients randomized to minimally invasive distal pancreatectomy with splenectomy achieved an R0 resection, as compared with 69% of those assigned to open distal pancreatectomy, meeting predefined criteria for noninferiority (P=0.039), reported Mohammed Abu Hilal, MD, PhD, of the Istituto Ospedaliero Fondazione Poliambulanza in Brescia, Italy.

The first-of-its-kind trial "can confirm that minimally invasive pancreatectomy is a safe, valid, efficient alternative" to open surgery for early-stage cancers in the body and tail of the pancreas, according to Hilal.

"This is confirmed by a noninferior radical resection rate, lymph node yield, and comparable survival," he said during a press briefing ahead of the American Society of Clinical Oncology (ASCO) annual meeting, to be held here June 2-6.

While the trial was not powered for survival, the disease-free and overall survival outcomes observed were no different between the minimally invasive group and open-surgery group, respectively:

• Disease-free survival: 44 vs 45 months (HR 0.97, 95% CI 0.67-1.42)
• Overall survival: 40 vs 39 months (HR 0.99, 95% CI 0.67-1.45)

And for lymph node yield, another measure of oncologic radicality, a median 22 lymph nodes were retrieved during surgery in the minimally invasive group versus 23 in the open-surgery group (P=0.89).

The trial also found no significant differences for intraperitoneal recurrence (41% vs 38% for the minimally invasive and open-surgery groups) and for serious intraoperative adverse events (18% vs 22%) such as bleeding, injuries to other organs, or conversion of laparoscopy to open surgery.

"This confirmatory study proves that minimally invasive surgical techniques are a safe and effective option for resectable pancreatic cancer," said ASCO-designated expert Jennifer Tseng, MD, in a press release.

"This randomized surgical trial will help both surgeons and patients feel comfortable that minimally invasive surgery, in expert hands, is not inferior to open surgery," said Tseng, a surgical oncologist at Boston Medical Center. "This may provide benefits like faster recovery time and less infection risk, without increasing cancer risk."

However, no difference in DIPLOMA was seen for time to functional recovery (5 days in each arm), which Hilal suggested could be due to a number of reasons, including the variance in standard hospital practice across the dozen nations participating in the trial.

In the U.S., just 12% of the nearly 65,000 adults expected to be diagnosed with pancreatic cancer in 2023 will have operable disease. While prognosis is dismal in late-stage disease -- where the disease often is first detected -- the 5-year survival rate for early-stage disease is 44% when surgery can be performed.

Initially adopted nearly 30 years ago, primarily for benign or borderline tumors, minimally invasive pancreatectomy has become more common in recent decades, according to Hilal. But only in the past 10 to 15 years has the approach been considered for malignancies.

"The main reason for this delay was the concern about the oncologic efficiency," he said.

In a from 2015, nearly one-third raised concerns about the safety and efficacy of the minimally invasive approach. On top of that, some trials in other cancers have failed to show equivalence with less-invasive approaches, and in some cases harm has been seen -- most notably, perhaps, in the randomized LACC trial for early cervical cancer.

DIPLOMA, a noninferiority trial, included 258 patients with operable pancreatic ductal adenocarcinoma from 35 centers across 12 countries. From May 2018 to May 2021, patients were randomized 1:1 to either minimally invasive distal pancreatectomy with splenectomy (laparoscopic or robot-assisted) or open distal pancreatectomy.

The modified intention-to-treat (ITT) population included 117 patients and 114 patients in the two groups, respectively, who ultimately underwent surgery. The study's primary endpoint was radical resection in the modified ITT group (R0, ≥1 mm distance between the tumor tissue and margin), and the 4% (90% CI -6 to 14) between-group difference fell within the prespecified threshold for noninferiority of -7%.

"Although we acknowledge that survival would have been the best primary endpoint, for this, thousands and thousands of patients are needed," said Hilal. But he pointed out that R0 resection has been demonstrated in studies to be a good surrogate that is "very closely" associated with survival.

According to the , eligible patients included adults with operable tumors in the tail or body of the pancreas, and those with borderline resectable disease were excluded.

Pathologists and nurses in the ward were blinded to treatment group, as were patients (using similar postoperative abdominal dressing). Follow-up was conducted at 2 weeks after surgery, and then at 1, 3, 6, and 12 months (when a CT scan was performed).

The researchers said they plan to continue following patients to assess outcomes at 3 and 5 years, and to perform additional analyses to determine if splenectomy is in fact necessary.

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