Recently, CCRT is still the standard treatment of patients with LACC [3–6], but the tumor control rate and long-term survival are still unsatisfactory, especially for those with stage IIIB or IVA,many of which have tumor residual, progression, even died shortly after CCRT [17]. Therefore, how to reduce the tumor residual and improve their survival is an urgent clinical problem to be resolved.
NACT can reduce the tumor load and lymph-vascular space involvement, increase the radiation sensitivity [18]. For many locally advanced tumors, NACT has been proved to improve the tumor control and survival, and has become the important part of standard treatment [9–10]. However, the role of NACT in cervical cancer is still unclear. A previous meta-analysis of 18 randomized rials found comparing to the radical radiotherapy alone, the addition of NACT can improve the survival for LACC in trials with chemotherapy cycle lengths ≤ 14 days or cisplatin dose intensities ≥ 25 mg/m2/week (HR = 0.83, P = 0.046) [19]. In another meta-analysis including early or advanced cervical cancer, the addition of NACT can improve the OS (HR = 0.77, P = 0.02) and progression free survival (HR = 0.75, P = 0.008) of patients undergoing radical surgery[20]. Marita et al. retrospectively analyzed the objective response, overall survival and disease specific survival of LACC patients, and found the NACT followed by CCRT results in higher response rates and improvements in disease free survival and disease specific survival compared with the CCRT alone [21]. Conversely, some studies deemed the NACT was detrimental to patients. Da Costa SCS, et al. found compared to the CCRT alone, the addition of NACT consisting of cisplatin and gemcitabine was associated with an inferior 3-year progression free survival ( 40.9% vs. 60.4%, HR = 1.84; P = 0.033) and overall survival (60.7% vs. 86.8%; HR = 2.79; P = 0.006), even the lower response rates at the end of treatment (56.3% vs. 80.3%; P = 0.008) [8]. NACT was also reported to be detrimental on survival if cisplatin dose intensities lower than 25 mg/m2/week (HR, 1.35; P = 0.002) or cycle lengths longer than 14 days (HR = 1.25; P = 0.005) [19] .
In light of the reported inconsistent effect of the NACT, it is still of great significance to determine the role and explore the optimal regimens of NACT for LACC. In this study, we found the patients received NACT-nPC followed by CCRT had a higher CR rate than others at the end of EBRT (45.0% vs. 23.2%; P = 0.002) and CCRT (93.3% vs. 82.6%, P = 0.033). At the end of the EBRT, the CR rate of NACT-nPC group was nearly twice that of the control group. We primarily attributed it to the higher therapeutic dose of nab-paclitaxel, whose recommended dose of 260 mg/m2 was nearly twice 135 mg/m2 of traditional paclitaxel, and the advantage of the higher dose translated into a better tumor regression rate. Secondly, the control group included some patients with CCRT alone, who has not completed the CCRT at this time.
After the treatment completion, the CR rate of the control group is 82.6%, similar with that of patients received CCRT alone in previous study [8]. We explain this as follows: 1) The control group in this study included some patients with CCRT alone; 2) NACT regimens in this group included traditional paclitaxel or liposomal paclitaxel combined with cisplatin, carboplatin or other platinum, which have been reported no advantage on survival for LACC [8, 13]; 3) the cisplatin dose intensities in this study was 17–25 mg/m2/week, lower than 25 mg/m2/week, which was the cut-off value of benefit [19]. However, a promising clinical CR rate of 93.3% in group of NACT-nPC was obtained. This result is higher than 56.3% − 86.54 % reported in previous literature [8, 22]. Besides the advantage of stronger dose intensities of nab- paclitaxel elaberated above, the following factors may also explain it: 1) the NACT reduced the tumor volume, and the massive tumor have more chance to be covered completely with radical radiation dose; 2) NACT reduced the hypoxia of tumor cells and increased its radiation sensitivity [23]; 3) The radiotherapy process from visiting the doctor to CT-simulation, target volume delineation, planning, verification and starting radiation took more than one month on average. During this period, patients with CCRT alone did not receive any treatment, while patients with NACT received chemotherapy usually in one week after the visit and simutaneously start the radiotherapy process. 1–2 cycles of NACT have been performed at the beginning of radiotherapy. Therefore, patients with NACT followed by CCRT received treatment earlier than CCRT alone.
The treatment response to NACT was an independent risk factor of prognosis for patients with LACC [22, 24]. A meta-analysis including 13 studies found the clinical response to NACT was associated with better overall survival (HR = 3.36, P < 0.00001) and disease free survival (HR = 2.36, P < 0.00001), and the pathological response also predicts favorable overall survival (HR = 5.45, P < 0.00001) and disease free survival (HR = 3.61, P < 0.00001) [22]. In another study, 58.9% of patients with IB2-IIA2 receiving platinum-based NACT achieved response and 8.7% of patients achieved pathologically CR. NACT responders showed significantly better overall survival (HR = 2.453, P = 0.024) and progression free survival (HR = 2.196, P < 0.013) [24]. We began to use nab-paclitaxel and cisplatin as the NACT from 2019, and the follow-up time was not enough to compare the survival differences between the two treatment schemes. However, compared with the control group, patients receiving NACT-nPC had higher local CR rate at the end of EBRT and CCRT. We speculate that patients receiving NACT-nPC followed by CCRT have better survival outcomes.
In this study, the dosage of nab-paclitaxel was higher than the traditional paclitaxel, which improved the CR rate of tumor, but did not improve the acute or chronic adverse events. On the contrary, with the preventive use of polyethylene glycol recombinant human granulocyte colony stimulating factor, the hematological toxicity was lower. Besides the hematological toxicity, grade 1–2 diarrhea is also common, which can be relieved after symptomatic treatment. In addition, NACT-nPC did not increase long-term toxicity.