Table 1.
Characteristics of included studies (n = 19)
| Author (year) | Sample size/no. of SBC patients included (%) | Study design | Country | Study population | SACT | Data source | Primary exposure | Exposures/covariates | Outcome of interest | Statistical analysis |
|---|---|---|---|---|---|---|---|---|---|---|
| Accordino et al. (2017) [26] | 4251/4521 (100) | Retrospective cohort | USA | Women > 66, confirmed stage IV diagnosis between January 2002–2011, who died by 31 December 2012 | Chemotherapy | SEER-Medicare | Time from diagnosis to death, costs of care, location of death | Age, year of diagnosis, marital status, race, hospital location (urban/rural), geographic region, comorbidities, HR status, No. of consultations | Receipt of end-of-life (EoL) care which included receipt of IV chemotherapy within 14 days of death | Logistic regression model to determine association between clinical, demographic and prognostic factors and receipt of EoL care |
| Alves et al. (2022) [33] | 296/2525 (12) | Analytical cross-sectional study | Brazil | Patients with a confirmed BC diagnosis and without treatment from January to December 2019 | Receipt of no SACT treatment | Cancer Hospital Registers (CHR) | - | Age group, race education, marital status, smoking status, alcohol status, region, family history, referral source, tumour, stage at diagnosis | Lack of access to BC treatment | Multivariate regression for factors associated with lack of access to SACT. odds ratio (OR) values with a 95% confidence interval (CI 95%), and estimated p-values |
| Cole et al. (2019) [34] | 65,380/601,680 (11) | Retrospective cohort | USA | Patients > 40 years with metastatic prostate, lung, colon and breast cancer, diagnosed from January 1, 2004, to December 31, 2015 | Chemotherapy | NCDB | Minority serving hospital (top decile) (MSH) | Age, race, year of diagnosis, insurance status, education income, comorbidities | Receipt of specialist palliative care (SPC) which included non-curative systemic chemotherapy | Multilevel logistic regression model which estimated odds of palliative care, adjusted for year of diagnosis, sex, race/ethnicity, insurance, income, educational level and cancer type |
| Falchook et al. (2017) [35] | 5855/28,731 (20) | Retrospective cohort | USA | Patients > 18 < 64 years at time of death, who died between 1 Jan 2007 and 31 Dec 2014, with metastatic lung, colorectal, breast, pancreatic or prostate cancer with a diagnosis code reflecting metastatic disease during the 12 months preceding death | Chemotherapy | HIRD | Not specified | Age, year of death, population density, geographical region | Receipt of end-of-life (EoL) care which included chemotherapy in the last 14 days of life | Modified Poisson regression models to estimate risk for each outcome, adjusted for age, sex, geographic region, rural/urban location, year of death and regional education and income measures |
| Ferreira et al. (2020) [36] | 10,816/151,931 (7) | Cross sectional | Brazil | Women > 18 > 70 diagnosed with breast cancer between 1998 and 2012 | Unspecified SACT | NCI HRC | Not specified | Referral route, stage, insurance status, family history, time between diagnosis and treatment, geographic region, marital status, education, race, age | Time between diagnosis and commencement of treatment < 60 days or > 60 days | Logistic regression of time between diagnosis and treatment adjusted for clinical and epidemiologic characteristics. Addition and removal of variables in the model with significance levels for the removal and addition of variables in the models were p ≤ 0.20 and p > 0.05, respectively |
| Giap et al. (2023) [27] | 60,685/60,685 (100%) | Retrospective cohort | USA | Patients aged > 18 years diagnosed with de novo stage IV breast cancer between 2010 and 2017 | Chemotherapy (non-curative) | NCDB | Race and ethnicity | Facility type, income, insurance, education, residential setting, diagnosis age, comorbidities, diagnosis year, tumour grade, metastasis location, tumour receptor types, prior treatment(s) | Receipt of palliative care which included non-curative systemic therapy | Multivariable logistic regression analysis to identify variables associated with receipt of palliative care |
| Ozmen et al. (2015) [37] | 29/1031 (3) | Questionnaire survey | Turkey | Women aged ≥ 18 years diagnosed with breast cancer within 6 months prior to questionnaire completion and undergoing/preparing for treatment | Unspecified SACT | Validated questionnaire | Not specified | Patient characteristics, symptom detection, first admission public/private hospital, surgical treatment, stage, lymph node involvement | Time to receipt of treatment defined as follows: (i) patient delay time (PDT), (ii) system delay time (SDT), and (iii) total delay time = sum of PDT and SDT | Chi-square tests and one-way analysis of variance (ANOVA) for group differences, principal components analysis for variable reduction and multiple regression analysis to build predictive models of PDT, SDT and TDT |
| Recondo et al. (2019) [38] | 268/13 (5) | Retrospective cohort | Argentina | Patients ≥ 18 years old with diagnosis of non-small cell lung cancer (NSCLC) or breast cancer, stages I to IV treated with chemotherapy from January 1, 2016 | Chemotherapy | Participant medical records | Not specified | Nationality, civil status, income, employment, transportation, travel time, stage, detection, performance status, treatment modality, chemotherapy provider | Time elapsed between diagnosis and receipt of treatment with chemotherapy | Kaplan–Meier curves were used to estimate patterns in time to diagnosis and to initial treatment and compared by the log rank test. Cox proportional hazard to explore association between health system and individual and sociodemographic and clinical variables |
| Sathe et al. (2023) [28] | 6802/6802 (100%) | Retrospective cohort | USA | Patients ≥ 18 years old, diagnosed with HR-positive, HER2-negative MBC between February 3, 2015 (first FDA approval of a CDK4/6i) and July 31, 2021 | Cyclin-dependent kinase 4 and 6 (CDK4 and CDK6) inhibitors | Flatiron health database (FHD) | Race | Age at MBC diagnosis, insurance coverage, site of treatment, performance status, year of metastatic diagnosis, the presence or absence of baseline leukopenia | Receipt of cyclin-dependent kinase 4 and 6 (CDK4 and CDK6) inhibitors palbociclib, ribociclib or abemaciclib documented in the FHD at any time after a MBC diagnosis | Multivariable logistic regression models were developed to analyse the association between CDK4/6i use and sociodemographic, clinical characteristics |
| Shih et al. (2009) [39] | 42,804/207,581 (21) | Retrospective cohort | USA | Patients ≥ 18 years old newly diagnosed with metastatic breast cancer, colorectal cancer and NHL, who received immunotherapy treatment between 1998 and 2004 | Immunotherapy | NCDB | Not specified | Age, race, ethnicity, year of diagnosis, insurance status, income, education, facility type | Receipt of immunotherapy following cancer diagnosis | Logistic regressions to examine factors associated with immunotherapy use in each of the three cancers. Separate analysis for the elderly and non-elderly samples to avoid the issue of near collinearity between age and insurance variables |
| Shiovitz et al. (2015) [40] | 3583/76,259 (5) | Retrospective cohort | USA | Patients ≥ 18 years diagnosed with metastatic breast, colon, lung, prostate, ovarian and gastric cancers between 2001 and 2007 | Chemotherapy | SEER-Medicare | Race (NHW/AI/Ans) | Age, cancer type, geographic region, year of diagnosis | Utilisation of cancer directed therapy which included chemotherapy | Logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (95% CI) |
| Statler et al. (2019) [30] | 6234/6234 (100) | Retrospective cohort | USA | Patients 18 years or older diagnosed with stage IV (defined as metastatic to a distant site, M1 per American Joint Committee on Cancer TNM Staging Criteria), hormone receptor-positive (ER + and/or PR +) and HER2 + breast cancer who received treatment between 2010 and 2015 | Not specified | NCDB | Not specified | Age, race/ethnicity, comorbidities, insurance status, income, facility type, distance to treatment, grade, sites of metastases and treatment | Treatment receipt for chemotherapy and hormone (endocrine) therapy | Multivariable logistic regression analyses were conducted to identify independent predictors of treatment receipt (chemotherapy vs. hormonal therapy) |
| Skinner et al. (2021) [32] | 608/608 (100) | Retrospective cohort | USA | Women aged ≥ 18 years, diagnosed with metastatic triple negative breast cancer (mTNBC) between 1 January 2010 and 31 January 2016 | Unspecified SACT | Vector Oncology Data Warehouse | Not specified | Age, race, BMI, Insurance, region, stage, performance, comorbidities, site of metastases | Treatment receipt (PFS, OS) | Logistic regression methods were used to evaluate predictors of receipt of systemic anticancer therapy |
| Small et al. (2012) [41] | 57,148/773,233 (7) | Retrospective cohort | USA | Patients > 18 diagnosed with stage IV cancer of kidney, uterus, NSCLC, SCLC, rectum, colon, prostate, breast and cervix between 2000 and 2008 who did not receive any first‐course therapy | Unspecified SACT | NCDB | Not specified | Age, race, ethnicity, insurance status, education, income | Receipt of no first course anticancer therapy | Log‐binomial regression to estimate prevalence ratios (PRs) with 95% confidence limits (95% CL) relating the percentages of patients receiving no first‐course therapy versus any therapy for stage IV cancer among categories of various socioeconomic and demographic variables. Statistical significance was defined as p < .05 |
| Vas Luiz et al. (2015) [31] | 4364/4364 (100) | Retrospective cohort | USA | Women > 66 with a first invasive metastatic breast cancer diagnosed between October 1998 and December 2009 enrolled in Parts A/B Medicare | Immunotherapy | SEER-Medicare | Race (White/Black) | Age, marital status, income, education, year of diagnosis, location of residence (metro/nonmetro), geographical location (SEER region), comorbidity, grade, HR status | Time to trastuzumab initiation and utilisation of trastuzumab | Wilcoxon signed-rank tests and multivariable linear regression to examine utilisation adjusting for exposure variables stratified by HR status |
| Vyas et al. (2021) [5] | 1089/1089 (100%) | Retrospective cohort | USA | Women aged > 65 years diagnosed with HER2-negative MBC during 2010–2013 | Unspecified SACT | SEER-Medicare | Not specified |
Predisposing characteristics comprised age at diagnosis, race/ethnicity, whilst enabling characteristics included marital status, household income and education Need-related factors included HR status, grade of tumour, comorbidity scores, performance status and number of sites with cancer metastasis External care environmental factors comprised the location of residence, SEER region and census level information on the number of hospitals offering oncology services |
Receipt of guideline-concordant initial treatment within the first 6 months of a cancer diagnosis |
Multivariable logistic regression to identify the significant predictors of guideline-concordant treatment and a non-linear decomposition method to examine disparities by HR status |
| Wan & Jubelirer (2015) [35] | 4533/4533 (100) | Retrospective cohort | USA | Women > 66 diagnosed with stage IV metastatic breast cancer between 1992 and 2002 | Chemotherapy | SEER-Medicare | Not specified | Age, race, ethnicity, year of diagnosis, income, marital status, HR status, comorbidities, rural/urban, geographical location (SEER region), area chemotherapy rate, travel time, oncologist provision, hospice provision | Receipt of chemotherapy within 6 months (183 days) of diagnosis | Multivariate logistic regression aggregate models with interaction terms and subgroup analyses |
| Wang & Du (2015) [42] | 1100/25,128 (4) | Retrospective cohort | USA | Women > 65 diagnosed with hormone receptor-positive breast cancer aged between 2006 and 2009 with Part-D claims up to December 2010 | Hormone therapy | SEER-Medicare | Not specified | Age, race, marital status, comorbidity, SES, geographical location (SEER region), location of residence (urban/rural), year of diagnosis, stage, grade, lymph node involvement | Receipt of hormone therapy and overall use of hormone therapy 1 year post initiation (stratified by chemotherapy use) | Multivariate logistic regression assessed variation associated with the use of hormone therapy, SERM and AIs, respectively, adjusted for age, gender, race, marriage status, SEER registry area, year of diagnosis, tumour stage, tumour size, radiation therapy status, surgery status and comorbidity |
| Wolfson et al. (2015) [43] | 1441/75,987 (4) | Retrospective cohort | USA | Patients aged > 22 < 65 with newly diagnosed adult-onset breast, cervical colorectal, gastric, hepatobiliary, lung, oral, and pancreatic cancer between 1998 and 2008 | Unspecified SACT | NCI LAC | Not specified | Age, race/ethnicity, SES, distance to nearest NCI CCC | Receipt of care which included including SACT at National Cancer Institute Comprehensive Cancer Centre (NCI CCC) | Logistic regression analysis for multivariate modelling of likelihood of receiving care at an NCICCC. Two-sided tests with p < 0.05 were considered statistically significant |