Before you invest, you may want to review the fund’s prospectus, which contains more information about the fund and its risks. You can find the fund’s prospectus and other information about the fund, including the fund’s reports to shareholders and statement of additional information, online at insurancefunds.mfs.com. You can also get this information at no cost by calling 1-800-225-2606 or by sending an e-mail request to orderliterature@mfs.com. The fund’s prospectus and statement of additional information, both dated April 30, 2019, as may be amended or supplemented from time to time, are incorporated by reference into this summary prospectus.

CLASS	TICKER SYMBOL
Initial Class	N/A
Service Class	N/A

Beginning on January 1, 2021, as permitted by regulations adopted by the U.S. Securities and Exchange Commission, the insurance company that offers your contract may determine that it will no longer send you paper copies of the fund's annual and semiannual shareholder reports unless you specifically request paper copies from the insurance company or from your financial intermediary. Instead, the shareholder reports will be made available on a Web site (insurancefunds.mfs.com or other Web site of which you will be notified), and the insurance company will notify you by mail each time a report is posted and provide you with a Web site link to access the report. Instructions for requesting paper copies will be provided by your insurance company or financial intermediary.

If you already elected to receive shareholder reports by email, you will not be affected by this change and you need not take any action. If your insurance company or financial intermediary offers electronic delivery, you may elect to receive shareholder reports and other communications from the insurance company or financial intermediary by email by following the instructions provided by the insurance company or financial intermediary.

Beginning on January 1, 2019, you may elect to receive all future reports in paper free of charge from the insurance company or financial intermediary. You can inform the insurance company or financial intermediary that you wish to continue receiving paper copies of your shareholder reports by contacting your insurance company or financial intermediary. Your election to receive reports in paper will apply to all funds held in your account with your insurance company or financial intermediary.

Summary of Key Information

Investment Objective

The fund’s investment objective is to seek capital appreciation.

Fees and Expenses

This table describes the fees and expenses that you may pay when you hold shares of the fund. If the fees and expenses imposed by the insurance company that issued your variable contracts or other eligible investor through which the fund is offered were included, your expenses would be higher.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment):
		Initial Class	Service Class
	Management Fee	0.90%	0.90%
	Distribution and/or Service (12b-1) Fees	None	0.25%
	Other Expenses	0.15%	0.15%
	Total Annual Fund Operating Expenses	1.05%	1.30%
	Fee Reductions and/or Expense Reimbursements¹	(0.17)%	(0.17)%
	Total Annual Fund Operating Expenses After Fee Reductions and/or Expense Reimbursements	0.88%	1.13%

Massachusetts Financial Services Company has agreed in writing to bear the fund's expenses, excluding interest, taxes, extraordinary expenses, brokerage and transaction costs, and investment-related expenses (such as interest and borrowing expenses incurred in connection with the fund's investment activity), such that "Total Annual Fund Operating Expenses" do not exceed 0.88% of the class' average daily net assets annually for Initial Class shares and 1.13% of the class' average daily net assets annually for Service Class shares. This written agreement will continue until modified by the fund’s Board of Trustees, but such agreement will continue until at least April 30, 2020.

FCI-SUM-100819 Page 1 of 3

MFS International Growth Portfolio

Example

This example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. If the fees and expenses imposed by the insurance company that issued your variable contracts or other eligible investor through which an investment in the fund is made were included, your expenses would be higher.

The example assumes that: you invest $10,000 in the fund for the time periods indicated and you redeem your shares at the end of the time periods; your investment has a 5% return each year; and the fund’s operating expenses remain the same.

Although your actual costs will likely be higher or lower, under these assumptions your costs would be:

	1 YEAR	3 YEARS	5 YEARS	10 YEARS
Initial Class Shares	$90	$317	$563	$1,267
Service Class Shares	$115	$395	$697	$1,553

Portfolio Turnover

The fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs. These transaction costs, which are not reflected in “Annual Fund Operating Expenses” or in the “Example,” affect the fund’s performance. During the most recent fiscal year, the fund’s portfolio turnover rate was 18% of the average value of its portfolio.

Principal Investment Strategies

MFS (Massachusetts Financial Services Company, the fund's investment adviser) normally invests the fund’s assets primarily in foreign equity securities, including emerging market equity securities. Equity securities include common stocks and other securities that represent an ownership interest (or right to acquire an ownership interest) in a company or other issuer.

MFS focuses on investing the fund’s assets in the stocks of companies it believes to have above average earnings growth potential compared to other companies (growth companies).

MFS may invest the fund’s assets in securities of companies of any size.

MFS normally invests the fund's assets across different industries, sectors, countries, and regions, but MFS may invest a significant percentage of the fund’s assets in issuers in a single industry, sector, country, or region.

MFS uses an active bottom-up investment approach to buying and selling investments for the fund. Investments are selected primarily based on fundamental analysis of individual issuers. Quantitative screening tools that systematically evaluate issuers may also be considered.

Principal Risks

As with any mutual fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency.

The principal risks of investing in the fund are:

Equity Market Risk/Company Risk: Equity markets are volatile and can decline significantly in response to, or investor perceptions of, issuer, market, economic, industry, political, regulatory, geopolitical, and other conditions. These conditions can affect a single issuer or type of security, issuers within a broad market sector, industry or geographic region, or the equity markets in general. Certain events can have a dramatic adverse effect on equity markets and may lead to periods of high volatility in an equity market or a segment of an equity market.

Growth Company Risk: The stocks of growth companies can be more sensitive to the company’s earnings and more volatile than the market in general.

Foreign Risk: Exposure to foreign markets through issuers or currencies can involve additional risks relating to market, economic, industry, political, regulatory, geopolitical, and other conditions. These factors can make foreign investments, especially those in emerging markets, more volatile and less liquid than U.S. investments. In addition, foreign markets can react differently to these conditions than the U.S. market.

Emerging Markets Risk: Investments in emerging markets, especially frontier markets, can involve additional and greater risks than the risks associated with investments in developed foreign markets. Emerging markets can have less developed markets, greater custody and operational risk, less developed legal, regulatory, and accounting systems, and greater political, social, geopolitical, and economic instability than developed markets.

Currency Risk: The value of foreign currencies relative to the U.S. dollar fluctuates in response to market, economic, industry, political, regulatory, geopolitical, and other conditions, and changes in currency exchange rates impact the financial condition of companies or other issuers and may change the value in U.S. dollars of investments denominated in foreign currencies.

Focus Risk: Issuers in a single industry, sector, country, or region can react similarly to market, currency, political, economic, regulatory, geopolitical, and other conditions, and the fund's performance will be affected by the conditions in the industries, sectors, countries and regions to which the fund is exposed.

Liquidity Risk: It may be difficult to value, and it may not be possible to sell, certain investments, types of investments, and/or investments in certain segments of the market, and the fund may have to sell certain of these investments at prices or times that are not advantageous in order to meet redemptions or other cash needs.

Investment Selection Risk: MFS' investment analysis and its selection of investments may not produce the intended results and/or can lead to an investment focus that results in the fund underperforming other funds with similar investment strategies and/or underperforming the markets in which the fund invests.

Performance Information

The bar chart and performance table below are intended to provide some indication of the risks of investing in the fund by showing changes in the fund’s performance over time and how the fund's performance over time compares with that of a broad measure of market performance.

The fund’s past performance does not necessarily indicate how the fund will perform in the future. Updated performance is available at mfs.com or by calling 1-877-411-3325. If the fees and expenses imposed by the insurance company that issued your variable contracts or other eligible investor through which an investment in the fund is made were included, they would reduce the returns shown.

Page 2 of 3

MFS International Growth Portfolio

Initial Class Bar Chart.

The total return for the three-month period ended March 31, 2019, was 12.60%. During the period(s) shown in the bar chart, the highest quarterly return was 23.08% (for the calendar quarter ended June 30, 2009) and the lowest quarterly return was (19.62)% (for the calendar quarter ended September 30, 2011).

Performance Table.

Average Annual Total Returns
(For the Periods Ended December 31, 2018)

	1 YEAR	5 YEARS	10 YEARS
Initial Class Shares	(9.02)%	3.35%	8.60%
Service Class Shares	(9.30)%	3.08%	8.32%
Index Comparison (Reflects no deduction for fees, expenses, or taxes)
MSCI All Country World (ex-US) Growth Index (net div)	(14.43)%	1.69%	7.15%

Investment Adviser

MFS serves as the investment adviser for the fund.

Portfolio Manager(s)

Portfolio Manager	Since	Title
David Antonelli	2010	Vice Chairman of MFS
Matthew Barrett	2015	Investment Officer of MFS
Kevin Dwan	2012	Investment Officer of MFS

Effective April 15, 2021, David Antonelli will no longer be a portfolio manager of the fund.

Purchase and Sale of Fund Shares

You should consult with the insurance company that issued your variable contract, or other eligible investor through which your investment in the fund is made, for minimum investment requirements and redemption procedures.

Taxes

You should consult with the insurance company that issued your variable contract, or other eligible investor through which your investment in the fund is made, to understand the tax treatment of your investment.

Payments to Financial Intermediaries

The fund, MFS, and/or its affiliates may make payments to insurance companies, other financial intermediaries, and all of their affiliates, for distribution and/or other services. These payments may create a conflict of interest for the insurance company or other financial intermediary to include the fund as an investment option in its product or to recommend the fund over another investment option. Ask your financial intermediary or insurance company, or visit your financial intermediary's or insurance company's Web site, for more information.

Page 3 of 3