Background
Colorectal cancer, as a very common malignant tumor in the world, is
always damaging people’s lives and properties. According to the cancer
data just released at the beginning of 20241, as of
2022, colorectal cancer has the second highest incidence rate among all
malignant tumors in the whole population, with the fourth highest
incidence rate among women and the second highest incidence rate among
men. The mortality rate was the fourth highest in the population as a
whole. Therefore, it seems that colorectal cancer poses a huge health
hazard to citizens, which should not be underestimated. In China, the
5-year survival rate of colorectal cancer patients is between 50% and
60%, which is slightly lower than that of the United States, Japan, and
most European countries2,3,4. In addition, first-line
treatment for metastatic colorectal cancer is effective, but benefit
from back-line treatment remains limited5. At the same
time, our country patients are mostly have good physical constitutions
and have a higher likelihood of receiving back-line
treatments6, making more appropriate treatments
especially important for them. Around 2020, the advent of immunotherapy
brought a new light to the treatment of malignant tumors. In particular,
the discovery of immune checkpoint inhibitors, such as PD-L1 and CTLA-4,
has been of great benefit to patients with malignant tumors in terms of
prolonging survival time and improving their quality of
life7,8. The combination of immunotherapy with
conventional systemic chemotherapy has been particularly successful in
lung cancer. However, in colorectal cancer patients, the efficacy of
immunotherapy remains controversial due to issues such as its specific
molecular mechanisms9. In particular, most experts
have not reached a consensus on whether to combine immunotherapy in the
back-line treatment of advanced colorectal cancer patients, the
selection of immune checkpoint inhibitors of different pathways, or even
the different types of immune checkpoint inhibitors at home and abroad.
In addition, it is well known that immunotherapy is a therapeutic mode
to inhibit immune escape and improve the tumor microenvironment to play
an anti-tumor role. Therefore, many studies have confirmed that tumor
microenvironment is particularly important for immunotherapy of tumors.
However, for colorectal cancer, there are currently limited biomarkers
that can predict disease outcome10.It has been shown
that microsatellite status, TMB11, POLE/POLD1
mutation12, and PD-L1
expression13can assess the effectiveness of treatment
with immune checkpoint inhibitors to varying
degrees14,15,16.However, the factors sometimes fail
to identify the dominant population that will ultimately benefit from
immunotherapy due to individual differences and so on. Currently, there
is an increasing number of research that suggests that inflammatory
markers such as the degree of lymphocyte and neutrophil infiltration can
largely predict the outcome of malignant tumors, especially
immunotherapy, and the evidence for this claim is inextricably linked to
the doctrine of the tumor microenvironment17.Thus, the
inflammatory index in the patient’s body is closely related to the
prognosis of colorectal cancer patients18. For
patients with early-stage colorectal cancer, perioperative NLR may have
a certain relationship with their recurrence and
prognosis19. However, NLR have not received a great
deal of attention and there is no uniformity for colorectal cancer
patients in advanced stages, especially those receiving back-line
immunotherapy. In this paper, through a retrospective case study, we
analyzed that NLR in patients with treated advanced colorectal cancer
can serve as an important predictor of the efficacy of immunotherapy,
and at the same time confirmed the relationship between microsatellite
status and the prognosis of immunotherapy, which further indicated that
the degree of infiltration of inflammatory markers in the tumor
microenvironment, such as lymphocytes and neutrophils, is closely
related to the therapeutic efficacy of immune checkpoint inhibitors.