Highlights of Upcoming 2017 GI Cancers Symposium

Three presentations to be featured at the 2017 Gastrointestinal Cancers Symposium were singled out as newsworthy at a pre-meeting presscast. The presentations focused on:

  • Use of PET scans after induction chemotherapy to guide further treatment for esophageal cancer
  • A watch-and-wait approach that can avoid surgery in some patients with rectal cancer, and
  • The life-prolonging effects of physical activity for patients with advanced colorectal cancer

PET Scan Guidance (Abstract 1)

Use of PET scans to assess response to induction chemotherapy may allow tailoring of subsequent chemotherapy, vastly improving outcomes for patients with esophageal cancer, according to results of a phase II trial.

“PET scans may prove to be a valuable tool to help oncologists fine-tune the use of chemotherapy for esophageal cancer and maximize the benefits of chemotherapy for each individual patient,” said ASCO Expert Nancy Baxter, MD, moderator of the presscast. “This is heartening evidence for a new approach to treating a disease where innovation is sorely needed.”

Standard treatment for stage II-III esophageal and gastroesophageal junction (GEJ) cancers consists of 5.5 weeks of chemoradiation followed by surgery. Thus far, there is no way to predict which of several chemotherapy regimens will be most effective for an individual patient. The present study utilized PET imaging in 257 patients with stage II-III esophageal and GEJ cancers who were randomized to one of two induction chemotherapy regimens (modified FOLFOX-6 or carboplatin/paclitaxel).

After an initial PET scan at baseline, a second PET scan was obtained following the first few cycles of induction chemotherapy. If the PET scan suggested the regimen was effective, patients continued the same regimen during chemoradiation. If the PET scan suggested that the regimen was not effective, chemotherapy was switched to the other regimen during chemoradiation. Based on PET scan results, switching occurred in 29/129 patients randomized to FOLFOX-6 and 49/128 randomized to carboplatin/paclitaxel.

This study found that PET used to guide therapy after induction chemotherapy achieved improved pathological complete response (pCR) — a surrogate marker for survival in esophageal cancer after induction chemotherapy — compared with previous studies that did not utilize the PET-guided approach.

The pCR rate for non-responding patients was 19% for those who switched to carboplatin/paclitaxel and 17% for those who switched to FOLFOX-6. The pCR rate for all PET non-responding patients taken together was 18%. These pCR rates compare favorably with a 5% pCR rate previously reported in PET nonresponders to induction chemotherapy.

For PET responders, pCR was 26%, and for all patients on study, pCR was 23%.

This is one of the first studies to show the benefit of PET imaging in informing pre-surgery treatment decisions for this type of cancer.

“This strategy [using PET after induction chemotherapy to assess response] can be used in clinical trials to identify the most effective chemotherapy regimens,” said lead author Karyn A. Goodman, MD, University of Colorado School of Medicine, Aurora, CO.

Watch-and-Wait Approach for Rectal Cancer (Abstract 521)

It is possible for strictly selected patients with stage II-IV rectal cancer — that is, patients with no evidence of residual cancer following induction therapy — to forego surgery, according to a large, observational, “real world” study. Using a “watch-and-wait” approach following initial treatment with chemotherapy and/or radiation did not compromise 3-year survival rates.

“Some people with rectal cancer undergo surgery after chemoradiation therapy, even though it may not be necessary,” said study co-author Maxime van der Valk, MD, International Watch and Wait Database (IWWD) Consortium, Leiden University Medical Center, Leiden, the Netherlands. “From the data we have now, it seems that a watch-and-wait may be safe in selected patients with rectal cancer, but it is too soon to say whether this approach should be routinely offered.”

The study was based on an analysis of 679 patients of a total of 802 patients enrolled in the IWWD database (35 institutions from 11 countries). All patients had no signs of residual cancer after induction treatment, as assessed by physical exam, endoscopy, or MRI/CT scans following chemotherapy and radiation. All patients were managed by watch-and-wait care, which included extensive monitoring for recurrence every 3 months by endoscopy, MRI scan, and physical exam for the first 2 years.

At a median follow-up of 2.6 years, 25% of patients underwent delayed surgery due to local recurrence, and distant metastasis was reported in 7%. The 3-year survival rate was 92% among all patients and 87% among those who had a recurrence. These data are comparable with historic data from patients who undergo surgery.

This is not a practice-changing trial, and “watch and wait” is not yet included in treatment guidelines, but it does tell us more about which patients should be considered for this strategy, Dr. van der Walk said.

Dr. Baxter, session moderator, said: “Five years ago, it would have been considered heresy to treat rectal cancer without surgery. Over the past few years, we are beginning to consider this but there are no standard protocols or guidelines. It is an evolving area and patient selection will be critical.”

Physical Activity Associated with Improved Survival in Advanced CRC (Abstract 659)

Even though it may be difficult to exercise with advanced colorectal cancer (CRC), moderate physical activity appears to be life-extending, according to a smaller trial embedded in a large phase III trial of 1,231 patients designed to evaluate chemotherapy for metastatic CRC.

Prior to starting chemotherapy, patients reported their physical activity level on a questionnaire. The researchers determined the level of physical activity per week for each patient. Patients who were engaged in 30 or more minutes each day of moderate physical activity (i.e., walking, cleaning, or gardening) had a 19% reduction in mortality and a 16% reduction in disease progression compared with those who spent the least amount of time engaging in moderate physical activity (i.e., 30 minutes of moderate physical activity per week).

Engaging in the physical activity also was linked to improved survival; patients who walked 4 or more hours per week had a greater than 20% improvement in overall survival, and those who participated in 5 or more hours a week of nonvigorous physical activity (i.e. yoga or walking) had a 25% improvement in overall survival.

“These findings suggest that as little as 30 minutes a day of moderate physical activity may improve outcomes,” said lead author Brendan John Guercio, MD, resident at Brigham & Women’s Hospital in Boston, MA. “While exercise is by no means a substitute for chemotherapy, patients can experience a wide range of benefits from as little as 30 minutes of exercise a day.”

No association was found between vigorous physical activity and cancer outcomes, but the numbers of patients engaging in vigorous physical activity were too small to show statistical significance.

This is one of the first studies to show a link between level of physical activity in patients with CRC and distant metastases. Prospective studies are needed to confirm these associations.

The 2017 Gastrointestinal Cancers Symposium is jointly sponsored by the American Gastroenterological Association (AGA), the American Society of Clinical Oncology (ASCO), the American Society for Radiation Oncology (ASTRO), and the Society of Surgical Oncology (SGO) and will take place January 19-21, 2017, at the Moscone Convention Center in San Francisco.

by John McCleery

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