Locally Advanced Pancreatic Cancer

TREATMENT

CASE CONTINUED

After an abdominal CT is obtained, the patient is referred to an outpatient oncologist because of concern for pancreatic adenocarcinoma. After consultation, the patient is advised to obtain EUS with biopsy and to return immediately afterwards for further treatment planning. The pathology report following EUS confirms that the mass is a poorly differentiated PDA. The patient’s case is discussed at a multidisciplinary meeting with radiation, surgical, and medical oncology. The abdominal CT and PET-CT scan are thoroughly reviewed. After imaging review, the multidisciplinary team concludes that the tumor is in contact with the SMA at 120° and with the common hepatic artery without extension in the celiac axis and without evidence of metastasis.

• What is the appropriate management of borderline resectable pancreatic cancer?

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BORDERLINE RESECTABLE CANCER

Patients who have nonmetastatic disease and are deemed resectable and without contraindications to surgery or high-risk features, as defined by NCCN guidelines, should proceed directly to surgery. A large body of evidence suggests that complete surgical resection with negative margins is a significant predictor of survival and currently provides the only option for cure.^57–59 Despite the curative intent of surgery, the rate of recurrence remains high in patients who undergo surgical resection. Even in patients with negative resection margins (R0 resection), the 5-year survival is 20% to 30%, with a median survival ranging from 12 to 25 months, suggesting the presence of regional and distant occult disease at the time of diagnosis.^60–62

Additionally, in half the patients who undergo surgical resection with resultant positive microscopic (R1 resection) or gross (R2 resection) margins, the median survival is no greater than 12 months. In this subset of patients, clinical outcomes are similar to outcomes in patients with locally advanced and metastatic pancreatic cancer, suggesting that upfront surgery and adjuvant therapy may not be the ideal therapeutic option. This raises 2 important points: first, resectability should be assessed carefully in all patients with LAPC, and second, for those patients who are deemed borderline resectable, neoadjuvant therapy should be considered.⁶³ Borderline resectability is defined as tumor abutment ≤ 180° of the celiac artery, and tumor abutment of the superior mesenteric vein /portal vein of > 180° or abutting ≤ 180° with irregularity of the vein with or without thrombosis with anatomical structures that still allows for safe and complete resection and vein reconstruction (Table 2).

Neoadjuvant Therapy

The goal of neoadjuvant therapy is to minimize the negative impact of upfront surgery in patients who have a high likelihood of having microscopic or grossly positive margins. Research has suggested that neoadjuvant therapy may improve resectability, decrease the rate of recurrence, and improve overall survival.^64–66

There is no clear consensus on the ideal management of patients with borderline resectable disease. However, expert guidelines are in agreement that upfront surgery in patients with LAPC is not appropriate, as most patients will not be able to achieve an R0 resection.⁶⁷ As staging and management of patients with LAPC is difficult, expertise of a multidisciplinary team can be helpful.⁶⁸

Several studies and the NCCN guidelines support the use of neoadjuvant therapy in patients deemed borderline resectable.^69,70 Treatment of borderline resectable disease is similar to unresectable LAPC and generally involves 2 chemotherapy treatment backbones: FOLFIRINOX (folinic acid [leucovorin], fluorouracil [5-FU], irinotecan, and oxaliplatin) or gemcitabine-based therapy.

Phase 1 to 2/3 clinical trials conducted by Conroy et al from 2005 to 2011, including the landmark ACCORD-11 trial, established the safety and role of FOLFIRINOX in metastatic pancreatic cancer and also demonstrated an improved overall survival with the use of this therapy in these patients.^71,72 These findings led to interest in FOLFIRINOX as a neoadjuvant therapy for patients with LAPC. Since then, multiple prospective and retrospective studies have shown that 54% to 100% of patients with borderline resectable LAPC who were treated with FOLFIRINOX were down-staged significantly enough to undergo resection. Of those patients, more than 90% had a R0 resection following surgery (Table 3).^73–79

Data over the past 7 years suggests that neoadjuvant FOLFIRINOX improves overall survival and resectability in patients with borderline disease. However, treatment with FOLFIRINOX is not without limitations. FOLFIRINOX is associated with higher rates of febrile neutropenia, thrombocytopenia, diarrhea, and sensory neuropathy as compared with gemcitabine-based therapy.⁷² Other less commonly observed toxicities associated with FOLFIRINOX include mucositis, hand-foot syndrome, pulmonary toxicity, and alopecia. Dose-attenuated FOLFIRINOX-based regimens, including those that exclude the bolus fluorouracil dose and augment upfront filgrastim, have demonstrated improved safety and comparable efficacy as compared to standard FOLFIRINOX.⁸⁰

Gemcitabine has been the fundamental treatment backbone for PDA since the results of the phase 3 CONKO-001 trial were published.⁸¹ Gemcitabine is a pyrimidine antimetabolite and potent inhibitor of DNA polymerase and ribonucleotide reductase.⁸² In recent years, multiple combination therapies with gemcitabine have been investigated, including regimens with nab-paclitaxel, oxaliplatin, or docetaxel. Resection rates and negative margin outcomes have been shown to be comparable to patients who received FOLFIRINOX in the neoadjuvant setting with borderline locally advanced disease.^83–85 In addition to having a more tolerable side effect profile in comparison to fluorouracil-based regimens, gemcitabine is considered to be a potent radiosensitizer.⁸⁶ For this reason, studies have also investigated the role of radiotherapy in conjunction with gemcitabine, revealing negative margin resection rates above 80% in patients with borderline resectable disease.^87,88