Table 1.
Characteristics and quality assessment of the included studies
| Study, year, country | Study type, period | Resectability status | Definition of status | Neoadjuvant treatment (proportion + protocol) | Quality score |
|---|---|---|---|---|---|
| Barbier et al. [23], 2011, France | Retro, 1997–2006 | RPC | Tumor surrounding ≤ 180° of the circumference of SMV/PV, no tumor contact to CA and SMA, and no occlusion of SMV/PV confluence. |
Chemo: 100%, 5-FU + cisplatine Radio: 100%, 45 Gy |
14 |
| Papalezova et al. [24], 2012, America | Retro, 1999–2007 | RPC | No evidence of tumor extension to SMA, CA, CHA, SMV, and PV. Radiographically borderline resectable or unresectable disease was excluded. |
Chemo: 100%, capecitabine or infusional 5-FU Radio: 100%, 45 or 50.4 Gy |
13 |
| Tajima et al. [25], 2012, Japan | Retro, 2006–2009 | RPC/BRPC | No detailed statement, but potentially resectable diseases were included. |
Chemo: 100%, GEM + S-1 Radio: 0% |
12 |
| Cho et al. [26], 2013, Korea | Retro, 2002–2011 | BRPC | Tumor encasement of a short segment of CHA, without evidence of tumor extension to CA; tumor abutment of the SMA involving < 180° of the circumference; or short-segment occlusion of SMV/PV, allowing for vascular reconstruction. |
Chemo: 100%, GEM alone (most) or GEM + cisplatin or GEM + capecitabine Radio: 100%, 45 or 50.4 or 58.4 Gy |
14 |
| Jiang et al. [27], 2013, China | Retro, 2004–2010 | RPC | Tumors not involving major vascular structures including CA, SMA, and SMV/PV. |
Chemo: 72%, GEMa Radio: 28%, 54 Gy |
14 |
| Patel et al. [28], 2014, America | Retro, 1995–2010 | RPC/BRPC | Tumor abutment involving SMV/PV with or without narrowing or short-segment occlusion of the lumen allowing for safe resection, or tumor abutment of the SMA ≤ 180° of the circumference, or gastroduodenal artery encasement up to the hepatic artery with either short segment encasement or direct abutment of the hepatic artery, without extension to CA. |
Chemo: 100%, GEM + taxotere + capecitabine Radio: 98%, 37.5 (30–50.5) Gy |
12 |
| Roland et al. [30], 2015, America | Pro, 1990–2008 | RPC | No statement, but patients with borderline-resectable or locally advanced disease were excluded. |
Chemo: 100%, GEM, 5- FU or capecitabine Radio: 98%, 30 or 50.4 Gy |
12 |
| Lee et al. [29], 2015, Korea | Retro, 2000–2013 | RPC/BRPC | Tumor abutment (≤ 50% of the circumference) or encasement (> 50% of the circumference) of the SMV or PV. |
Chemo: 100%, GEM alone (most), GEM + cisplatin or GEM + capecitabine Radio: 100%, 45 or 50.4 or 58.4 Gy |
12 |
| Sho et al. [31], 2015, Japan | Retro, 2006–2013 | RPC | RPC—no tumor contact to CA, SMA, CHA, SMV/PV, or venous abutment of SMV/PV without distortion or narrowing. |
Chemo: 100%, GEM Radio: 100%, 50 or 54 Gy |
12 |
| BRPC | BRPC—tumor with encasement of a short segment of CHA without evidence of tumor extension to CA, or tumor abutment of the SMA within 180° of circumference. | ||||
| Golcher et al. [36], 2015, Germany | Pro, RCT, 2003–2009 | RPC | No organ infiltration except the duodenum and maximal involvement of peripancreatic vessels ≤ 180°. |
Chemo: 88%, GEM + cisplatin Radio: 88%, 50.4 Gy |
Low risk of biasb |
| Hirono et al. [32], 2016, Japan | Retro, 2000–2013 | BRPC | Tumor abutment of SMA within 180° of the circumference, or CHA without extension of hepatic artery bifurcation, or CA without involvement of the aorta. |
Chemo: 100%, GEM + S-1 or S-1 Radio: 57%, 50 Gy |
13 |
| Masui et al. [33], 2016, Japan | Pro, 2006–2010 | RPC/BRPC | Severe unilateral SMV/PV impingement, circumferential SMA abutment of less than 180°, or encasement of a short segment of the CHA. |
Chemo: 100%, GEM + S-1 Radio: 0%, NA |
14 |
| Ielpo et al. [3], 2017, Spain | Pro, 2007–2016 |
RPC BRPC |
RPC—no radiographic evidence of vascular invasion. BRPC—venous involvement of the SMV/PV; tumor abutment of the SMA within 180° of the circumference. |
Chemo: 100%, GEM + nab-paclitaxel Radio: 44%, ≤ 52 Gy |
15 |
| Murakami et al. [35], 2017, Japan | Retro, 2002–2015 | BRPC | Tumor contact with SMA of ≤ 180° or tumor contact with CHA without extension to the CA or hepatic artery bifurcation, allowing for safe and complete resection and reconstruction. |
Chemo: 100%, GEM + S-1 Radio: 0% |
13 |
| Fujii et al. [34], 2017, Japan | Pro, 2001–2013 | RPC | RPC—lesions without adjacent major vasculature including SMV/PV, SMA, CHA, and CA. |
Chemo: 100%, S-1 Radio: 100%, 50.4 Gy |
15 |
|
RPC/BRPC BRPC |
BR-PV—lesions involved exclusively with the SMV/PV system. BR-A—lesions involving gastroduodenal artery encasement up to the hepatic artery without extension to CA or ≤ 180° of tumor abutment to SMA. |
||||
| Jang et al. [9], 2018, Korea | Pro, RCT 2012–2014 | BRPC | Tumor abutment of SMA within 180 degrees of the circumference; tumor abutment of SMV/PV with impingement and narrowing of the lumen, or short-segment venous occlusion, allowing for safe resection and reconstruction. |
Chemo: 100%, GEM Radio: 100%, 45 Gy |
Low risk of biasb |
| Reni et al. [12], 2018, Italy | Pro, RCT 2010–2015 | RPC | Lesions with the absence of invasion of superior mesenteric artery or vein, portal vein, coeliac artery, or hepatic artery. |
Chemo: 100%, cisplatin + epirubicin + capecitabine + GEM Radio: 0% |
Low risk of biasb |
Abbreviations: RPC resectable pancreatic cancer, BRPC borderline resectable pancreatic cancer, Retro retrospective, Pro prospective, RCT randomized controlled trial, Chemo chemotherapy, Radio radiotherapy, GEM gemcitabine, SMV superior mesenteric vein, PV portal vein, CA celiac axis, CHA common hepatic artery
a72% of patients only received neoadjuvant chemotherapy while 28% of patients received neoadjuvant radiotherapy alone
bTrials are RCTs evaluated by Cochrane Collaboration’s tool and the detailed result of assessment is showed in the Additional file 1: Table S6